as·​say | \ a-ˈsā How to pronounce assay (audio) , ˈa-ˌsā How to pronounce assay (audio) \
assayed; assaying; assays

Definition of assay

 (Entry 1 of 2)

transitive verb

1a : to analyze (something, such as an ore) for one or more specific components assayed the gold to determine its purity
b : to judge the worth of : estimate assay the results of the new changes
2 : try, attempt Again Israel assayed to reply, but could not.— Herman Melville

intransitive verb

: to prove up in an assay


as·​say | \ ˈa-ˌsā How to pronounce assay (audio) , a-ˈsā How to pronounce assay (audio) \

Definition of assay (Entry 2 of 2)

1 : examination and determination as to characteristics (such as weight, measure, or quality)
2 : analysis (as of an ore or drug) to determine the presence, absence, or quantity of one or more components also : a test used in this analysis
3 : a substance to be assayed also : the tabulated result of assaying
4 archaic : trial, attempt

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Other Words from assay


assayer noun

Did You Know?


Usage experts warn against confusing the verbs "assay" and "essay." Some confusion shouldn't be surprising, since the two words look alike and derive from the same root, the Middle French word essai, meaning "test" or "effort" (a root that in turn comes from Late Latin exagium, meaning "act of weighing"). At one time, the two terms were synonyms, sharing the meaning "try" or "attempt," but many modern usage commentators recommend that you differentiate the two words, using "essay" when you mean "to try or attempt" (as in "he will essay a dramatic role for the first time") and "assay" to mean "to test or evaluate" (as in "the blood was assayed to detect the presence of the antibody").

Examples of assay in a Sentence

Verb They assayed the gold to determine its purity. the company assayed a sample of the rock to see if it contained gold in quantities worth mining Noun a metallurgist did an assay on the metal and determined it contained nickel the poem about a frustrated man's last assay at greatness
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Recent Examples on the Web: Verb With spectrometers for assaying elements in the regolith, the briefcase-size rover hopes to make the most of the 14-Earth-day lunar day. Sanjay Kumar, Science | AAAS, "'Failure is part of the game': Indian spacecraft presumed lost after moon landing attempt," 7 Sep. 2019 This Saturday, as a tribute to Previn’s memory at the opening weekend of Tanglewood, the Boston Symphony will assay the concerto, with Mutter as soloist. New York Times, "The Week in Arts: Sarah Jessica Parker Back for More ‘Divorce’; a Farewell to ‘My Fair Lady’," 29 June 2019 But interoperability—from ad-blocking to switching app stores—is a means by which customers can assay real counteroffers. The Economist, "Regulating Big Tech makes them stronger, so they need competition instead," 6 June 2019 After giving the foragers a day to recover from their treatments, the researchers assayed pathogen loads across all of the ants in the colony. Diana Gitig, Ars Technica, "Sick ants stay away from the kids," 26 Nov. 2018 At the Pantages, the role is assayed by Adrianna Hicks, an ensemble player in the Broadway revival who hasn’t quite made the leap to headliner. Charles Mcnulty,, "'The Color Purple' national tour turns down the wattage — and burns a little less brightly," 30 May 2018 That was followed by another sweaty hour in which Hinterhäuser assayed all six of Ustvolskaya’s piano sonatas, written between 1947 and 1988, with no break between them. Mark Swed,, "This year's Ojai Music Festival was bright, and dark, and very very hot," 12 June 2018 David Lord and a team at Sandia National Laboratories have been working on finding and developing methods for analyzing oils from different fields to quickly assay their chemical constituents. Alexis C. Madrigal, The Atlantic, "The Great Crude-Oil Fireball Test," 5 Feb. 2018 One challenge was to precisely assay the uranium isotopes, which could shed light on the material's source; on at least one measurement, COE scientists came out tops. Richard Stone, Science | AAAS, "U.S.-China mission rushes bomb-grade nuclear fuel out of Africa," 31 Aug. 2017 Recent Examples on the Web: Noun In order to prove that the test works, researchers collected nearly 12,000 specimens from 3,300 patients, comparing the results to three different research assays. San Diego Union-Tribune, "New test from San Diego’s Hologic is first in U.S. to help detect new STD threat," 2 Aug. 2019 What the blood assays for the tau protein, the main component of tangles in the brain, tell us is little less certain. The Conversation,, "Here’s what we know about blood tests for Alzheimer’s," 10 Aug. 2019 For each patient, the scientists combined the founder mutations to form a personalized assay, which could then be used to pick up signs of breast cancer DNA in blood samples. Alice Park, Time, "Promising Blood Test Could Help to Predict Breast Cancer Recurrence," 8 Aug. 2019 Only three labs nationwide use modern assays to screen for HIV. Richard Stone, Science | AAAS, "Exclusive: North Korea claimed to be free of HIV. But infections appear to be surging," 24 June 2019 Krammer used a novel assay to measure the hemagglutinin stalk antibodies. Debbie Ponchner, Scientific American, "New Finding Advances the Search for a Universal Flu Vaccine," 3 June 2019 The company develops receptor assays, computer screening and antibody discovery technologies to help companies seeking to get prescription drug approvals. San Diego Union-Tribune, "How the 16 highest-paid CEOs of San Diego public companies made their money," 14 July 2019 Since May, the results of 70 leaf assays have come in: some of the Ozark Chinquapin Foundation’s test plot trees are even more genetically resistant than Chinese chestnut, which does not succumb to chestnut blight. Robert Langellier, National Geographic, "A legendary Ozark chestnut tree, thought extinct, is rediscovered," 24 June 2019 Microarrays for running assays on large numbers of genes at once were brand-new. Quanta Magazine, "Wanted: More Data, the Dirtier the Better," 6 June 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'assay.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of assay


14th century, in the meaning defined at transitive sense 2


14th century, in the meaning defined at sense 4

History and Etymology for assay

Noun and Verb

Middle English, from Anglo-French assai, essai — more at essay entry 1

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Statistics for assay

Last Updated

19 Sep 2019

Time Traveler for assay

The first known use of assay was in the 14th century

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More Definitions for assay


How to pronounce assay (audio) How to pronounce assay (audio)

English Language Learners Definition of assay

technical : to test something (such as a metal or drug) to find out what it contains


as·​say | \ ˈas-ˌā How to pronounce assay (audio) , a-ˈsā How to pronounce assay (audio) \

Medical Definition of assay

 (Entry 1 of 2)

1 : examination and determination as to characteristics (as weight, measure, or quality)
2 : analysis (as of a drug) to determine the presence, absence, or quantity of one or more components — compare bioassay
3 : a substance to be assayed also : the tabulated result of assaying
as·​say | \ a-ˈsā How to pronounce assay (audio) , ˈas-ˌā How to pronounce assay (audio) \

Medical Definition of assay (Entry 2 of 2)

: to analyze (an impure substance or mixture) for one or more specific components the sample was assayed for drug content

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More from Merriam-Webster on assay

Thesaurus: All synonyms and antonyms for assay

Rhyming Dictionary: Words that rhyme with assay

Spanish Central: Translation of assay

Nglish: Translation of assay for Spanish Speakers

Britannica English: Translation of assay for Arabic Speakers

Comments on assay

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something of little or no value

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