[verb a-sey; noun as-ey, a-sey]

verb (used with object)

verb (used without object)

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


Nearby words

  1. assault course,
  2. assault jacket,
  3. assault rifle,
  4. assault weapon,
  5. assaultive,
  6. assay cup,
  7. assay groove,
  8. assay office,
  9. assay ton,
  10. assaying

Origin of assay

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

Related formsas·say·a·ble, adjectiveas·say·er, nounun·as·sayed, adjectiveun·as·say·ing, adjective

Can be confusedassay essay Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for assay

British Dictionary definitions for assay


verb (əˈseɪ)

to subject (a substance, such as silver or gold) to chemical analysis, as in the determination of the amount of impurity
(tr) to attempt (something or to do something)
(tr; may take a clause as object) to test, analyse, or evaluateto assay the significance of early childhood experience

noun (əˈseɪ, ˈæseɪ)

  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
a substance undergoing an analysis
a written report on the results of an analysis
a test
archaic an attempt
Derived Formsassayable, adjectiveassayer, noun

Word Origin for assay

C14: from Old Northern French assai; see essay

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

Word Origin and History for assay
Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for assay


[ăsā′, ă-sā]


Qualitative or quantitative analysis of a substance, especially of an ore or a drug, to determine its components.
A substance to be so analyzed.
The result of such an analysis.
An analysis or examination.


To subject a substance to chemical analysis.
To examine a person's capability by trial or experiment; put to a test.
To evaluate a situation; assess.
To attempt; try.
To be shown by analysis to contain a certain proportion of atoms, molecules, compounds, or precious metal.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for assay


[ăsā, ə-sā]

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