assay

1 of 2

verb

as·​say a-ˈsā  ˈa-ˌsā 

assayed; assaying; assays

transitive verb

1

a

: 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

assayer noun

assay

2 of 2

noun

as·​say ˈa-ˌsā  a-ˈsā 

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

Did you know?

Usage experts warn against confusing the verbs assay and essay. Some confusion shouldn’t be surprising; not only do the two somewhat uncommon words look and sound alike, they also come from the same root, the Middle French word essai, meaning "test" or "effort." (Essai, in turn, comes from the Late Latin word exagium, meaning "act of weighing.") At one time, the two terms were synonyms, sharing the meaning "try" or "attempt," but they are now typically differentiated, with essay meaning "to try or attempt" (as in "a comedic actor essaying her first dramatic role") and assay meaning "to test or evaluate" (as in "blood assayed to detect the presence of the antibody"). Of course, essay is more common as a noun referring to a short analytic or personal literary composition, but that’s another essay.

Synonyms

Verb

• analyze
• anatomize
• break down
• cut
• deconstruct
• dissect

Noun

• analysis
• anatomizing
• anatomy
• breakdown
• deconstruction
• dissection

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

Recent Examples on the Web

Verb

Exploring these boundaries creates a newly mobile human scale assaying territorial limits and equality. . . . —Sarah K. Rich, Artforum, 1 Apr. 2025

For example, cell viability assays measure the effect of a chemical on cell survival and growth. —Brad Reisfeld, The Conversation, 12 Mar. 2025

Noun

Paper has already shown promise as a substrate for sensors, biological assays, RF antennas, batteries, circuit boards, and smart packaging labels. —IEEE Spectrum, 29 Jan. 2013

But there is still much to learn about the actual fabrication costs of these assays, as well as practical properties like shelf life, sensitivity, and the reproducibility of their results. —IEEE Spectrum, 29 Jan. 2013

Word History

Etymology

Noun and Verb

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

First Known Use

Verb

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

Noun

14th century, in the meaning defined at sense 4

Phrases Containing assay

• enzyme-linked immunosorbent assay

Rhymes for assay

• bassi
• brassey
• brassy
• cassie
• chassis
• classy
• gassy
• glassy
• grassy
• lassie
• massy
• sassy

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Kids Definition

assay

1 of 2 noun

as·​say ˈas-ˌā 

a-ˈsā

: examination (as of an ore, metal, or drug) for the purpose of determining the presence, absence, or amount of one or more substances

assay

2 of 2 verb

as·​say a-ˈsā 

ˈas-ˌā

1

: try entry 1 sense 4, attempt

2

: to analyze (as an ore) for one or more valuable substances

assayer noun

Medical Definition

assay

1 of 2 noun

as·​say ˈas-ˌā  a-ˈsā 

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

assay

2 of 2 transitive verb

as·​say a-ˈsā  ˈas-ˌā 

: to analyze (an impure substance or mixture) for one or more specific components

the sample was assayed for drug content