'assay' originates from Old French, specifically the word 'essai' (and verbs like 'essayer' / 'assaier'), where the concept was 'a trial' or 'an attempt'; it also reflects influence from Vulgar Latin forms derived from Latin 'exagium'/'exigere' relating to weighing or testing.

'assay' changed from Old French 'essai'/'essayer' (trial, to try) into Middle English forms such as 'assayen' and eventually became the modern English word 'assay' (and by extension the gerund 'assaying').

Initially, it meant 'to weigh or try' (a physical trial or examination); over time it evolved into the current primary meanings 'to test or analyze (chemically or materially)' and the secondary meaning 'to attempt, try'.