'assayer' originates from Old French, specifically the word 'assayer' (also spelled 'essayer'), where the root 'essai' meant 'trial' or 'test'.

'assayer' changed from Middle English forms such as 'assaier' or 'assayen', which were derived from Old French 'essayer'/'assayer', and eventually became the modern English word 'assayer'.

Initially, it meant 'one who tries or tests' (in a general sense), but over time it evolved into its current meaning of 'a person who analyzes metals or ores to determine purity and content'.