Course terms

Two-alternative forced choice: two samples, and the assessor names the one that is stronger in a specified attribute. Guessing gives 1/2.

An alcohol-soluble extract obtained by washing a concrete with alcohol and removing the waxes.

A blend of materials that reads as one new smell rather than as its separate parts.

A material deliberately shared by two sub-accords, or placed between them in volatility, so that the drydown passes from one to the other without a gap.

The product of a second alcohol molecule replacing the hemiacetal's hydroxyl, with loss of water. Its formation is acid-catalyzed and reversible.

An ester formed from acetic acid and an alcohol. Linalyl acetate is the acetate of linalool.

The pure active in a concentrate divided by its total weight.

A correction factor, gamma, that multiplies the mole fraction when a mixture is not ideal. Above 1, a component escapes more than Raoult's law predicts; below 1, less.

Aroma extract dilution analysis: a GC-O method that repeatedly dilutes a sample to find the highest dilution at which each odorant can still be detected.

Mass of a substance per volume of air, here in mg per cubic meter. From a partial pressure p, it is pM/RT.

Breaking of a bond next to the atom carrying the charge or radical site after ionization, typically beside an oxygen. It gives a resonance-stabilized cation.

A warm, resinous, sweet composed effect, traditionally labdanum with vanilla-like materials. It has nothing to do with fossil amber or, strictly, ambergris.

A numbered release that changes the set of IFRA Standards, adding, revising or removing individual Standards.

A peak created by the analysis itself or by handling, such as a breakdown product formed in a hot injector.

A rating scale tied to fixed reference samples, so that a number means the same thing from one session to the next.

The region of chemical space where a model's training data give it grounds to predict. Outside it, predictions are extrapolations.

The suppliers qualified for a material, with the date and basis of each approval, consulted before any purchase.

A version of a formula grouped by sub-accord and role, kept beside the flat formula, so that substitutions can be made within a role.

A peak's area as a share of the total area. It is a relative signal and not automatically a weight percentage.

A defined odorous substance used as a fragrance ingredient, whether isolated from nature or made by synthesis.

k = A·exp(−Ea/RT): a rate constant rises exponentially with temperature, at a rate set by the activation energy Ea.

A line of code that stops the program if a stated condition is false. Here it encodes a value you worked out by hand.

Slow, spontaneous reaction with oxygen in air. Terpenes such as limonene and linalool are known to undergo it.

The single kind of difference explored in a variation series, such as amount of wood, type of musk or sweetness.

The ratio at which a pair gives the wanted effect, with neither partner standing out in a way you did not intend.

The least volatile part of a fragrance, which lingers longest.

The tallest peak in a mass spectrum, set to 100% relative abundance. It marks the most abundant fragment, not necessarily the most informative.

The documented decision that a batch meets its specification and can be used or sold.

The market fragrances chosen to define what a brief is reacting to or competing with, smelled and described before work begins.

In a Scheffé model, the coefficient of a product term such as x1x2. Positive means the two components together score higher than their average (synergy); negative, lower.

Mixing two dilutions of one material to reach a strength between them.

Identifying a smell without seeing its label, which tests recognition rather than memory of the name.

A test in which the person smelling does not know which sample is which, so expectation cannot drive the answer.

Keeping those taking part, and ideally those scoring, from knowing which sample is which.

A loose term for how a fragrance opens up and fills space, often as it warms or as a product is used. Its meaning varies by product type.

The burst of fragrance released when a product is diluted or used, such as in a shower.

The dose at which a cheaper-per-kg concentrate costs the same per unit as a dearer one at its own dose.

A material of intermediate volatility added so that a fragrance has no perceptible gap as it develops.

A written statement of what a fragrance must achieve: its purpose, audience, character and constraints.

Corrective and preventive action: steps to remove the cause of a problem that has occurred, and to prevent a similar one.

A molecule a fragrance company keeps for its own use rather than selling openly.

The solvent brought into a formula by its diluted lines.

The liquid that carries the fragrance in a finished product, such as ethanol, a cosmetic oil or a water-based system.

An influence of an earlier sample on the judgment of a later one, such as adaptation from the first strip smelled.

A registry number that identifies a chemical substance. It identifies the substance, not its quality or grade.

A supplier's statement of test results for one lot. It is checked against your specification; it does not replace it.

The score you would expect from guessing alone. In a triangle test, this is one in three.

A table showing which documents must be reviewed when a given item changes, such as the formula or a supplier.

A compound largely responsible for the recognizable smell of a material, sometimes present at a very low level.

The property of a molecule that cannot be superimposed on its mirror image, like a left and a right hand.

A plot of detector signal against time, in which each peak represents one or more components leaving the column.

The part of a molecule responsible for absorbing visible light, and so for its color. New chromophores can form when materials react.

A family typically built around citrus top notes, a floral heart and a mossy, woody base.

ln(P2/P1) = −(ΔHvap/R)(1/T2 − 1/T1): how vapor pressure changes with temperature, assuming the enthalpy of vaporization is constant over the range.

A natural extract made using carbon dioxide under pressure as the solvent.

Two or more compounds leaving the column at the same or nearly the same time, so that they appear as one peak or overlapping peaks.

How strongly a candle smells when unlit and when burning.

The idea that an odor is represented by the pattern of receptor types it activates, rather than by one dedicated receptor.

In version control, the short statement saved with each change saying why it was made. For formulas, the equivalent of the reason column in an iteration log.

A table whose entry in row i and column j is the fraction of pure material i in stock j. Multiplying it by the stock weights gives the pure amount of each material.

Recurring choices of material, proportion or structure that make a perfumer's work recognizable. It's usually seen in hindsight.

The manufacture of a fragrance concentrate in quantity from its raw materials, to a written instruction.

The undiluted fragrance formula, before it is diluted in alcohol or another carrier. Also called the fragrance oil or compound.

A waxy solvent extract of plant material, the intermediate from which an absolute is made.

Two materials you regularly mistake for each other, which are worth studying side by side.

The deliberate juxtaposition of two clearly separable characters, such as cold and warm or clean and animalic, which remain legible side by side.

A table showing, for each restricted substance, how much each formula line adds, so that the total can be compared with a limit.

A version made the same way but without the change being tested, which gives you something to compare with.

A strip of a single material kept beside a mixture so that you can tell what has changed.

The cost of the fragrance in one finished unit: cost per kg of concentrate × dose × fill weight, before other components.

The surfactant level above which micelles form. Below it, the surfactant cannot hold fragrance in micelles, which helps explain release on dilution.

When exposure to one smell also reduces sensitivity to a similar one.

The standardized distance between the sensation distributions of two products. It describes the products' difference independently of the test method used to measure it.

A short document explaining each column in a dataset: name, meaning, units and permitted values.

When information about the test set reaches the model during training, for example the same molecule appearing in both sets under different names. It inflates reported performance.

A dated record of each significant choice in a project, the options considered, the evidence used and who decided, so the reasoning can be reviewed later.

What is measured to see if the change had an effect, such as a rated intensity or a correct identification.

A word used to describe a smell, such as green, waxy or powdery.

The lowest concentration at which a person can tell that a smell is present, without necessarily naming it.

Any departure from an approved formula, method or specification.

A fragment whose mass points to a specific structural feature, used to confirm or reject a proposed identity.

Stereoisomers that are not mirror images, such as cis and trans forms. They generally differ in physical properties.

A list of the differences between two versions of a record. For a formula, keyed on material id, with each line marked added, removed, changed or unchanged.

How readily a smell spreads through air and is noticed away from its source.

A material mixed with solvent, stated as the percentage of material in the total weight.

A nearly odorless solvent, often shortened to DPG, used to dilute some materials and sold with some compounds.

Separating volatile materials by heating and condensing them. Steam distillation is the usual way of producing essential oils.

The later stage of a fragrance's development, after the top and much of the heart have gone.

A test with a known reference and two coded samples, one matching the reference. Guessing is right half the time.

In the formula list, D followed by a number: how many other copies of the formula exist. It falls when a copy is deleted, because it is counted, not stored.

A concentration term, abbreviated EDP, conventionally stronger than eau de toilette. Percentages vary by brand.

A concentration term, abbreviated EDT, conventionally lighter than eau de parfum. Percentages vary by brand.

The common GC-MS method that bombards molecules with electrons, usually at 70 eV, breaking them into reproducible fragments.

A quality perceived in a mixture that none of its components has alone, as when a few materials together read as a recognizable thing.

How completely a sample consists of one mirror-image form. A trace of a potent impurity or the opposite form can affect odor results.

The proportion of the two mirror-image forms of a compound, which can differ between natural and synthetic sources.

A pair of molecules that are mirror images of each other.

Enclosing fragrance in tiny capsules that attach to fabric and release when broken, for example by rubbing.

The heat needed to turn one mole of a liquid into vapor at constant pressure. The larger it is, the more steeply the vapor pressure rises with temperature.

A volatile natural material obtained by distillation or, for citrus peels, by mechanical expression.

A functional group made from an acid and an alcohol, common in fruity and floral materials, and subject to hydrolysis in water, acid or base.

An independent group that reviews research involving people. Also called an institutional review board in some countries.

A fragrance professional who assesses work in progress and links it to the brief, separately from the perfumer who composes it.

A chart of how strong a fragrance seems over time. It reflects perception as well as the physical evaporation of its materials.

The amount of a component leaving a surface per unit area per unit time. It is proportional to the component's partial pressure at the surface, through a mass-transfer coefficient that depends on air movement.

The standard uncertainty multiplied by a coverage factor k, commonly 2, giving an interval expected to contain a large fraction of plausible values, about 95% when the distribution is roughly normal.

A judgment shaped by what you expect to find rather than by what is present.

Guidance that research data be Findable, Accessible, Interoperable and Reusable, with emphasis on machines being able to find and use the data.

The set of all compositions that satisfy every constraint. In a linear program it is a convex polygon or polytope.

A material produced with the help of microorganisms grown on a feedstock, often sugar, then separated and purified.

The lowest temperature at which a liquid gives off enough vapor to ignite in the presence of a flame or spark.

The small binary errors in decimal arithmetic on computers, which make 0.1 + 0.2 slightly different from 0.3. Compare with a tolerance, or round before comparing.

The written list of materials and quantities that defines a fragrance, normally by weight.

The app's tool for calculated fields: arithmetic over one material's own fields, aggregates over every material, and calculations derived from saved aggregates.

In the app, a flag that makes a formula's entries read-only and refuses its deletion, until it is unlocked.

Supplying a manufacturer with compounded bases or premixes rather than the full formula, so that no single party holds it.

A family named after Fougère Royale, typically built around lavender, coumarin and mossy or woody notes.

In fragrance houses, the specialist who interprets client briefs, benchmarks the market, guides perfumers' work and selects which submissions go to the client. Usually not the person who writes the formulas.

A broad grouping of fragrances or materials by shared character, such as floral, woody or citrus.

Solvent present in a formula as its own line, as opposed to solvent carried inside a diluted material. Exchange Solvent can only draw on free solvent.

A specific arrangement of atoms in a molecule that largely determines how it reacts, such as an alcohol or an aldehyde.

The characteristic pattern of constituents in a natural material, compared with a reference to judge whether a sample is typical.

Gas chromatography in which part of the separated material goes to a sniffing port, so a person can describe what each peak smells like.

A difference in DNA sequence among people. In a receptor gene, it can change how a receptor responds to an odorant.

The Globally Harmonized System for classifying and labeling chemical hazards, whose pictograms and hazard statements appear on labels and SDSs.

An organized way of making products so that they are consistently produced and controlled to appropriate standards.

Informal term for allowing existing items to continue under older rules. Never assume it applies: check the specific rule and date.

The transition as one stage of a fragrance fades and the next takes over. A poor handover reads as a gap.

The air above the liquid in a container. Larger headspace means more oxygen in contact with the material.

The middle of a fragrance's development, also called a middle note, that emerges as the top fades.

The product of one alcohol molecule adding to an aldehyde's carbonyl. Usually unstable and in rapid equilibrium with the aldehyde and the alcohol.

The proportionality between partial pressure and mole fraction for a component at high dilution. It equals the activity coefficient at infinite dilution times the pure vapor pressure.

In organic chemistry, any atom in a molecule other than carbon or hydrogen, commonly oxygen, nitrogen or sulfur in fragrance materials.

A material that affects a composition at a very low share because its odor threshold is low. It is a working description and has no fixed cut-off.

How strongly a candle's fragrance fills a room while burning. Cold throw is its strength unlit.

A reaction with water that splits an ester back into its acid and alcohol, helped by acid or base.

A reactive oxidation product containing an O-O-H group, formed for instance when terpenes react with air.

A specific statement that a test could show to be wrong.

A dated record of what each change to a reconstruction was meant to test and what it showed, kept so the learning survives the reconstruction.

What the researcher changes on purpose, such as the dose of a material.

The time during which an antioxidant is consumed and oxidation stays slow. When the antioxidant runs out, the rate rises sharply.

A target composition that no non-negative set of stock weights can deliver, for example one asking for less solvent than the stocks already carry.

A person's voluntary agreement to take part, given after they have understood what's involved, its risks and their right to stop.

Disagreement or error in the training targets. Odor descriptors vary between people and panels, so the labels themselves are uncertain.

A cyclic ester. Gamma-lactones have a five-membered ring, and delta-lactones a six-membered ring.

A system at equilibrium responds to a change in concentration, temperature or pressure by shifting so as to oppose the change.

A similarity score between a measured mass spectrum and a reference spectrum. A candidate identification, not a proof.

An optimization whose objective and constraints are all linear in the unknowns. Its optimum, if one exists, lies at a vertex of the feasible region.

A retention index calculated with a straight-line formula, used for temperature-programmed runs, following van den Dool and Kratz.

The sub-accord whose removal makes a composition stop reading as itself. It is found by omission, and it is where precision matters most.

The weight of each original descriptor in a principal component. Large loadings of the same sign mean the descriptors rise together.

The logarithm of a substance's partition ratio between octanol and water. Higher values mean it favors oily environments.

A molecule containing a large ring, usually of 12 or more atoms in perfumery. Many musks are macrocyclic.

A musk with a large ring, commonly about 14 to 17 atoms, such as muscone or ambrettolide.

A reduction in the perceived intensity of one odor by the presence of another.

In the RUŌOD Lab app, a named, colored group of materials, such as a supplier's range or a family. A material belongs to one collection.

A fragmentation of carbonyl compounds with a hydrogen three carbons away: the hydrogen moves to the oxygen through a six-membered arrangement and an alkene is lost.

A cluster of surfactant molecules in water, with a water-repelling center in which fragrance materials can dissolve.

The smallest amount a supplier will sell. When it exceeds what a product needs, the unused remainder is a real cost.

The smallest amount you can weigh on a given scale with acceptable uncertainty. It is well above the scale's readability.

An experiment in which the response depends on the proportions of the components, which sum to one, rather than on their absolute amounts.

A trial version of a formula, short for modification. A project can involve many mods.

The record of a fragrance's development as branches of modifications from earlier versions, each with what it tested and what was kept, rather than a single line of versions.

The number of moles of one component divided by the total number of moles in the mixture. Raoult's law is written in mole fractions, not weight fractions.

A number calculated from a structure, such as molecular weight, an estimated log P or the count of hydrogen-bond donors, used to compare molecules or as input to a model.

The count of each kind of atom in a molecule, such as C10H18O for linalool.

The ion formed when a molecule loses one electron. Its mass-to-charge value gives the molecular mass, though it may be weak or absent.

A common bench term for a blend in which no part reads clearly, often from too many materials at similar levels.

A single aromatic molecule separated from a natural source, as opposed to the whole oil.

A synthetic molecule chemically the same as one found in nature. The molecule is the same even though the production route differs.

Undiluted. A neat material is at full strength, as supplied.

Storing each fact once, in the table it belongs to, so that changing it in one place cannot leave a contradiction elsewhere.

Rescaling every line of a formula by one factor so that the total reaches a chosen number, usually 100 or 1,000.

The assumption that there's no real difference, so results arise from chance alone. In a triangle test, it implies one in three correct.

A compound's concentration divided by its odor threshold, in the same medium. It's a simple estimate of whether a compound is likely to matter.

A material's concentration in air divided by its odor threshold. Above 1, it is in principle detectable.

A molecule that can be smelled. Molecules must be volatile enough to reach the nose in order to be odorants.

A protein in olfactory neurons that responds to certain odor molecules. Humans have hundreds of intact receptor genes.

A temporary loss of sensitivity to a smell after exposure to it. Also called olfactory adaptation or, informally, nose blindness.

Mixtures with no components in common that smell the same, as reported by Ravia and colleagues.

A protein on a sensory neuron in the nose that responds to certain odor molecules. Each neuron carries one receptor type.

The tactile metaphor a composition evokes — powdery, creamy, waxy, airy, sharp — defined in practice by reference smells and the materials that produce it.

Repeated, structured smelling. In clinical use it refers to a specific regimen for people with smell loss; in perfumery, to practice aimed at recognition and description.

The convergence reported by Weiss and colleagues, in which diverse mixtures with many equal-intensity components come to smell alike.

A sensory test that removes one component from a reconstituted mixture and asks whether panelists can detect the difference. It tests importance directly, where an OAV only predicts it.

An exact statement of how a concept will be measured in a particular study.

A change in a judgment caused by the position of a sample in a sequence.

The written sequence in which materials enter a production batch, chosen so solids dissolve, high-impact materials disperse and reactive pairs are not concentrated together.

Smelling by sniffing air in through the nostrils.

Chemical change caused by reaction with oxygen, which can alter a material's smell and in some cases raise its potential to cause skin allergy.

The probability of a result at least this extreme, if the null hypothesis were true. It isn't the probability that the hypothesis is true.

A controlled comparison of two materials and their mixture, used to learn what each does to the other.

A test showing two samples and asking which has more of a named attribute. Guessing is right half the time.

The share of a vapor's pressure contributed by one component. In an ideal mixture it is the component's mole fraction times its pure vapor pressure.

The ratio of a substance's concentration in two phases at equilibrium. LogP refers to the logarithm of its octanol-water value.

In the app, a field added from one material's Custom Fields section that only that material has.

A perfumer's organized arrangement of materials at the workbench, often tiered, named after the musical instrument.

Ethanol prepared for perfumery use, commonly the solvent for study dilutions.

The craft of composing scents from aromatic materials, and the study of those materials and how they behave.

In the app, a field defined in Tools → Material Fields that every material has, with its value stored on each material.

A laboratory measure of peroxides in a material, used as an indicator of oxidation.

The extent to which charge is unevenly distributed in a molecule. Polar substances tend to dissolve polar substances.

The place a product intends to occupy in a buyer's mind, relative to alternatives: for whom, for what occasion, and why this one.

The exponent n in Stevens' law, ψ = kC^n. For odor it is usually well below 1, so intensity grows much more slowly than concentration.

Personal protective equipment, such as gloves and eye protection. The SDS for a material states what is advised.

The smallest amount you trust yourself to weigh on your scale, found by your own repeatability test.

Writing down your hypothesis, method and analysis plan, with a date, before you collect data.

A blended accord or base kept ready to use as a single line in a formula. Sometimes called a base.

A column whose value identifies exactly one row and never changes, such as a material id. Other tables refer to the row through it.

A direction in descriptor space along which the samples vary most, uncorrelated with the components before it. The first explains the largest share of variance.

The EU and GB term for the documentation that must be kept available for a cosmetic product, including its safety report and evidence for its claims.

In the app, a batch size and concentration for a finished perfume, from which it works out the concentrate, the solvent and the scaling factor.

How far a fragrance can be noticed from the source, for a wearer or a test surface.

pd = (pc − p0)/(1 − p0), where pc is the proportion correct and p0 the guessing probability. It assumes each assessor either discriminates or guesses, which the Thurstonian model does not.

Testing a model on molecules evaluated after the model was built, by people who did not see its predictions. The strongest form of validation.

The record of where a value came from: a supplier's certificate, a paper, a measurement, a decision. It is what makes a value checkable later.

The weight of actual fragrance material in a line or formula, leaving out the solvent carried by its dilutions.

A dynamic headspace method that draws gas over a sample through an adsorbent trap, which collects volatiles over time.

The factor by which a rate increases for a 10 °C rise. It is not a constant: it depends on the activation energy and on the temperature.

A roughly equal mixture of two enantiomers.

A reaction carried forward by species with an unpaired electron, in which each propagation step regenerates a radical. A single initiation can convert many molecules before a termination ends the chain.

Assigning samples or orders by chance, so that unknown influences are not systematically linked to any one version.

An ideal-solution model: a component's partial vapor pressure equals its mole fraction times the vapor pressure of the pure material.

A series of mixtures of two materials at planned ratios, used to find where the balance is best.

The original, unchanged observations, before any calculation or tidying.

The written requirements a material must meet to be accepted: identity, physical constants, analytical limits, odor against a standard, and the documents that must accompany it.

The smallest step a scale displays, such as 0.01 g. It is not the same as its accuracy.

The measures a holder takes to keep information secret — access limits, agreements, marking, splitting — judged against the circumstances.

Trying to name a smell before you check its label, rather than smelling with the name in front of you.

The concentration at which a person can identify what the smell is. It is higher than the detection threshold.

A blend of identified components built to approximate a natural material, from analytical data. It tests which components carry the smell.

A specific, repeatable smell that anchors a descriptor, so that the word means something definite.

A physical sample kept to define a descriptor, such as a strip of a fixed blend for powdery, so that evaluators anchor the word to the same smell.

Changing an existing formula to meet a new requirement, such as a restriction, a cost target or a supply problem, while keeping its character as far as possible.

How strongly a detector responds to a compound compared with a reference compound at the same amount.

A solvent extract of a resin or other dried natural material.

A stored sample from a batch, kept so it can be compared or investigated later.

How much of a smell a substrate holds over time, usually assessed by perceived strength in simple tests.

A number that places a compound relative to n-alkane standards run under the same conditions, so results can be compared across laboratories.

The time a component takes to pass through the column. It depends on the method and instrument.

The reverse of a Diels–Alder reaction in an ionized cyclohexene ring, splitting it into a diene and an alkene, one of which keeps the charge.

Smell that reaches the receptors from the back of the mouth while you eat or drink.

The underlying reason a problem occurred, which if removed would prevent it from happening again.

A family name for damascones and related materials such as beta-damascenone. They are very potent and occur in rose oils.

The gradual growth of a project beyond what was agreed, usually through small requests without a matching change in fee or date.

A sample's coordinate on a principal component: its centered descriptor values multiplied by the loadings.

Safety data sheet: a supplier's standardized document on a substance's hazards and how to handle it.

The partial derivative of a result with respect to one input: how much the result changes per unit change in that input.

Making each dilution from the one before, such as stepping from 10% to 1% to 0.1%.

How much the optimal objective would improve if one constraint were relaxed by one unit. It prices what a requirement costs.

The change in a line's percentage caused by changes elsewhere in the formula, with its own weight unchanged.

A recurring way of solving problems — a structure, a contrast, a kind of restraint — rather than a recurring material or accord.

The trail of scent left in the air by a wearer. Usage varies, so define it when you use it.

A mixture design whose points are all combinations of proportions 0, 1/m, 2/m … 1 that sum to one. The {3,2} lattice has the three pure components and the three 50:50 binaries.

A drawing of a molecule in which carbon atoms are implied at line ends and corners, and most hydrogens are not shown.

An allergic response that can develop after exposure to a substance and can then recur at low levels of contact.

A specific smell, real or remembered, that a composition is trying to evoke, as opposed to an abstract adjective.

A dated record of what you smelled, how it was prepared, and what you noticed over time.

A narrow strip of absorbent paper for evaluating a material or fragrance. Also called a blotter, mouillette or touche.

A line notation that writes a molecule's structure as text, such as CC(C)=CCCC(C)(O)C=C for linalool. Stereochemistry can be included with @ and / \ signs.

A sampling method in which a coated fiber absorbs volatile compounds, then releases them into a GC injector. Abbreviated SPME.

Holding an oil-like material in water, often by way of a surfactant, so that the mixture stays clear.

A strip dipped in solvent alone, used to check whether you are really smelling the material.

A reduced or absent ability to smell one particular substance or group, while the sense of smell is otherwise normal.

The uncertainty of a result expressed as a standard deviation. For a reading known only to lie within ±a with equal likelihood, it is a/√3.

Rescaling each descriptor to unit variance before PCA, so that a descriptor rated on a wider range does not dominate merely because of its scale.

The thin coating inside a GC column. Compounds spend more or less time dissolved in it, which is what separates them.

The chance that a test will detect a real effect of a stated size. Small tests often have low power.

A psychophysical relationship in which perceived intensity grows as a power of stimulus concentration. For odors the exponent is commonly below 1.

A dilution kept ready to use, so that small amounts of a material can be weighed accurately.

The study of how a molecule's structure relates to how it smells. Often shortened to SOR.

A named group of materials within a larger formula, treated as a single unit while you compose and revise.

A fragrance sample sent to a client in response to a brief, typically one of several, selected from many internal trials.

The package that accompanies a fragrance submission: the brief's interpretation, the rationale, the evidence of testing, the constraints met and the open questions.

How well a material stays on a surface such as skin, hair or fabric over time.

How well a fragrance material stays on fibers after washing and drying.

The surface on which a fragrance is evaluated, such as paper, skin, hair or fabric.

Remaking a blend without one line at a time, to find which line causes a fault or carries an effect.

A reduction in the perceived intensity of a component when it is smelled in a mixture, compared with the same concentration alone. Common in odor mixtures.

A mixture smelling stronger, or more of a quality, than its components would predict. Claimed often in perfumery, demonstrated less often.

An odorous molecule made by chemical synthesis rather than isolated directly from a natural source.

To zero the scale with a container on it, so that only what you add is counted.

The schedule by which a GC oven heats during a run. Later compounds elute sooner and in sharper peaks than they would at a constant temperature.

How long a material stays perceptible on a substrate such as a smelling strip.

A plot or table of existing fragrances in a brief's space, placed by the dimensions the brief cares about, used to find where an answer can stand apart.

A model of discrimination in which each sample produces a sensation that varies randomly from moment to moment. Difference is measured as the distance between the two distributions in standard-deviation units, d′.

A natural material steeped in alcohol, which holds the extracted smell in solution.

The most volatile part of a fragrance, smelled first and gone relatively soon.

An estimate of the surface area contributed by polar atoms, computed from fragment contributions. Higher values mean more polar molecules.

A manufacturer's commercial name for a material, such as Hedione or Iso E Super, as distinct from its chemical name.

Under the EU directive, information that is secret, has commercial value because it is secret, and has been subject to reasonable steps to keep it secret.

A small, deliberately chosen set of materials, kept mainly at 10%, used for learning rather than production.

Exchange of the alcohol part of an ester with another alcohol, here usually ethanol. Reversible, slow without a catalyst.

A perfumer's descriptor for a light, airy effect in which a fragrance seems to have space within it. It is a judgment rather than a measured property.

A flag that marks a line as solvent: it adds weight to the formula but no pure fragrance material.

A method in which three samples are presented, two alike and one different, and the assessor picks the odd one out.

An early empirical idea, associated with Ohloff, relating ambergris odor in decalin-type molecules to three axial groups in a specific arrangement. Useful historically, but with exceptions.

A system with more unknown weights than independent targets. It has many solutions, and something else, such as cost or a minimum weight, must choose among them.

A requirement a brief does not write down but a client will judge by, such as price-tier materials, a heritage reference or a competitor to beat.

The pressure of a substance's vapor in equilibrium with its liquid at a given temperature. Higher vapor pressure means faster evaporation, all else equal.

A planned set of related compositions, each differing from a common base along a stated axis.

In the RUŌOD Lab formula list, V followed by a number: the formula's version, raised only by Duplicate and never renumbered.

How readily a material evaporates. More volatile materials reach the nose quickly and fade sooner.

The permitted deviation from a line's target weight in production, set by how much that deviation would change the product.

A loose family of synthetic materials with dry, radiant, woody and ambery effects. Ambroxan and Iso E Super are often discussed with them, though they differ.

One iteration of an accord in which a single planned change is made and compared with the previous version.

Using the highest credible composition value when an exact one isn't known, to avoid understating a substance.