[ verb a-sey; noun as-ey, a-sey ]
See synonyms for: assayassayableassayer on

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.

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

  2. to judge the quality of; assess; evaluate: to assay someone's efforts.

  3. to try or test; put to trial: to assay one's strength; to assay one's debating abilities.

  4. to attempt; try; essay: to assay a dance step.

verb (used without object)
  1. to contain, as shown by analysis, a certain proportion of usually precious metal.

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

  2. a substance undergoing analysis or trial.

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

  2. Archaic. examination; trial; attempt; essay.

Origin of assay

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

Other words from assay

  • as·say·a·ble, adjective
  • as·say·er, noun
  • un·as·sayed, adjective
  • un·as·say·ing, adjective

Words that may be confused with assay Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use assay in a sentence

British Dictionary definitions for assay


  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)

  1. (tr; may take a clause as object) to test, analyse, or evaluate: to assay the significance of early childhood experience

noun(əˈseɪ, ˈæseɪ)
    • an analysis, esp a determination of the amount of metal in an ore or the amounts of impurities in a precious metal

    • (as modifier): an assay office

  1. a substance undergoing an analysis

  1. a written report on the results of an analysis

  2. a test

  3. archaic an attempt

Origin of assay

C14: from Old Northern French assai; see essay

Derived forms of assay

  • assayable, adjective
  • assayer, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for assay


[ ăsā, 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.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.