assay

American  

[a-sey, as-ey, a-sey] / æˈseɪ, ˈæs eɪ, æˈseɪ /

verb (used with object)

1. to examine or analyze.

   to assay a situation; to assay an event.

2. Metallurgy. to analyze (an ore, alloy, etc.) in order to determine the quantity of gold, silver, or other metal in it.

3. Pharmacology. to subject (a drug) to an analysis for the determination of its potency or composition.

4. to judge the quality of; assess; evaluate.

   to assay someone's efforts.

5. to try or test; put to trial.

   to assay one's strength; to assay one's debating abilities.

6. to attempt; try; essay.

   to assay a dance step.

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verb (used without object)

1. to contain, as shown by analysis, a certain proportion of usually precious metal.

noun

1. Metallurgy. determination of the amount of metal, especially gold or silver, in an ore, alloy, etc.

2. a substance undergoing analysis or trial.

3. a detailed report of the findings in assaying a substance.

4. Archaic. examination; trial; attempt; essay.

assay British  

verb

1. to subject (a substance, such as silver or gold) to chemical analysis, as in the determination of the amount of impurity

2. (tr) to attempt (something or to do something)

3. (tr; may take a clause as object) to test, analyse, or evaluate

   to assay the significance of early childhood experience

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noun

1. 1. an analysis, esp a determination of the amount of metal in an ore or the amounts of impurities in a precious metal

   2. ( as modifier )

      an assay office

2. a substance undergoing an analysis

3. a written report on the results of an analysis

4. a test

5. archaic an attempt

assay Scientific  

/ ăs′ā,ə-sā′ /

1. A quantitative determination of the amount of a given substance in a particular sample. Assays are regularly used to determine the purity of precious metals. They can be performed by wet methods or dry methods. In the wet method, the sample is dissolved in a reagent, like an acid, until the purified metal is separated out. In the dry method, the sample is mixed with a flux (a substance such as borax or silica that helps lower the melting temperature) and then the sample is heated to the point where impurities in the metal fuse with the flux, leaving the purified metal as a residue.

2. A bioassay.

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Other Word Forms

• assayable adjective
• assayer noun
• unassayed adjective
• unassaying adjective

Etymology

Origin of assay

1250–1300; Middle English < Middle French; variant of essay

Example Sentences

After measuring ethanol levels using an enzymatic assay, the team estimated daily alcohol intake for several nectar-feeding species based on their caloric needs.

From Science Daily • Mar. 25, 2026

Dash, whose team includes former software engineers from Moderna, automates common laboratory tests such as Elisa, or enzyme-linked immunosorbent assay, which is used for tasks such as evaluating a drug’s safety and efficacy.

From The Wall Street Journal • Jul. 23, 2025

We set up an inhibition assay in test tubes.

From Salon • Dec. 16, 2024

They developed an assay that can be used to screen drugs to see if they restore protein mobility by comparing each drug's effect on a simple biomarker with surface cysteines to one without.

From Science Daily • Nov. 27, 2024

By the mast pond, where the great spars of ships lay refracted, we saw a little girl with a bucket, a vain and minute assay at extinguishing the flames.

From "The Astonishing Life of Octavian Nothing, Traitor to the Nation, Volume II: The Kingdom on the Waves" by M.T. Anderson