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 How does the saliva test differ from a standard nasal swab assay for COVID-19? Tanya Lewis, Scientific American, "COVID-19 Spit Tests Used by NBA Are Now Authorized by FDA," 20 Aug. 2020 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 Recent Examples on the Web: Noun Then—if that test result is unclear or is positive, which mine was—additional testing can come in the form of the Western immunoblot assay, which tests for immunoglobulin M (IgM) or immunoglobulin G (IgG) response antibodies. Kate Fridkis, SELF, "If It Isn’t Chronic Lyme, What Is It?," 14 Apr. 2021 According to federal guidelines, the assay should not be used to identify potentially infected students. New York Times, "Why Virus Tests at One Elite School Ran Afoul of Regulators," 30 Mar. 2021 To combat that issue, the swabs Rubin used in the station-sweeping assay are double-headed. Shannon Hall, Scientific American, "NASA Will Map Every Living Thing on the International Space Station," 11 Mar. 2021 When the results were compared with a highly reliable assay, positive results were aligned 94% of the time, and negative results in 98% of cases. Emma Court,, "U.S. Approves First At-Home Test Kit for Detecting Covid-19," 18 Nov. 2020 To understand antibody effectiveness against the new variant, UCSF scientists did a common experiment called a neutralization assay. Erin Allday, San Francisco Chronicle, "California coronavirus variant is resistant to antibodies, but vaccines should still work," 24 Feb. 2021 Like other antibody tests, the assay could also be used to identify potential plasma donors., "Hong Kong Mulls Stiffer Fines; Vietnam Flight Halt: Virus Update," 1 Dec. 2020 That [fourth case]was not a TaqPath assay, so there was no reason for the lab to even question it. Joe Carlson, Star Tribune, "COVID test used in Minnesota may offer clues about new strain," 17 Jan. 2021 His team is trying to develop an assay that could be used to test for variant viruses in wastewater from community sewage systems. Helen Branswell, STAT, "With limited surveillance of Covid-19 variant, it’s déjà vu all over again," 31 Dec. 2020

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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Time Traveler for assay

Time Traveler

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

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Cite this Entry

“Assay.” Dictionary, Merriam-Webster, Accessed 7 May. 2021.

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More Definitions for assay



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

Nglish: Translation of assay for Spanish Speakers

Britannica English: Translation of assay for Arabic Speakers

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