'assayable' originates from English, formed by adding the suffix '-able' to the verb 'assay'; the verb 'assay' comes from Old French 'assaier' (also attested as 'essai'), ultimately from Late Latin/medieval Latin roots related to weighing or testing.

'assay' changed from Old French 'assaier'/'essai' into Middle English forms such as 'assayen' or 'assay', and the adjective 'assayable' was later formed in English by adding the productive adjectival suffix '-able'.

Initially related to 'trying' or 'weighing' (a trial or test), its sense narrowed to technical testing (especially of metals and chemical composition); 'assayable' now means 'able to be tested or analyzed'.