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

verb (used with object)

verb (used without object)

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


Origin of assay

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

Related forms

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

Can be confused

assay essay Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for assaying

British Dictionary definitions for assaying


verb (əˈseɪ)

noun (əˈseɪ, ˈæseɪ)

Derived Forms

assayable, 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

Medicine definitions for assaying


[ ăsā′, ă-sā ]



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

Science definitions for assaying


[ 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.