English Reference
noun · verb

assay

n. · v.
US /ˈæsi/ UK /ɐsˈeɪ/ as·say UK spelling assayed, assays

  1. 01 C1 Advanced Technical Science

    n.a test to find out how much of a specific metal or chemical is in a sample.

    n.a procedure in metallurgy or biology for measuring the presence, amount, or functional activity of a target entity.

    Simple

    The laboratory performed an assay to check the purity of the gold coin.

    In context

    The environmental agency conducted a biological assay to determine the concentration of pollutants in the river water.

    Usage

    Often used with 'of' to specify the substance being tested.

  2. 02 C1 Advanced Technical Science

    v.to test a metal or ore to see what it contains.

    v.to examine or analyze a substance, typically a metal or drug, to determine its components or quality.

    Simple

    The miners sent the rocks to be assayed for silver content.

    In context

    Before the pharmaceutical company could release the new drug, they had to assay every batch for chemical consistency.

    Usage

    This verb is transitive and requires a direct object, usually the material being tested.

  3. 03 C2 Proficiency LiteraryFormal

    v.to try to do something, especially something difficult.

    v.to attempt or try a task or action; often implies a trial or testing of one's own abilities.

    Simple

    He did not assay the steep climb until the weather improved.

    In context

    The young knight was eager to assay his strength against the seasoned champions in the tournament.

    Teacher's tip

    In modern English, 'attempt' is much more common; 'assay' in this sense is restricted to high-register literature or historical contexts.

The cellular and in vitro biogenesis assays developed by the team make it possible to measure how their properties change during assembly and maintenance.

Phys.org· 20 Aug 2026

The strip’s chemically treated nitrocellulose paper functions as an immunochromatographic assay that can detect the presence of Borrelia burgdorferi .

Smithsonian Magazine· 31 Jul 2026

From Middle English assay (noun) and assayen (verb), from Anglo-Norman assai (noun) and Anglo-Norman assaier (verb), from Old French essai. Doublet of essay.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Old French essai
Level C2 · Proficiency
Frequency Frequent
Updated