'assemblement' originates from Old French, specifically the word 'assemblement', where 'assembler' meant 'to bring together'.

'assemblement' changed from Old French 'assemblement' (from verb 'assembler') and entered Middle English usage as an occasional or literary/archaic noun meaning 'a gathering', eventually becoming rare in modern English while related forms like 'assembly' became standard.

Initially, it meant 'the act of bringing together' or 'a gathering', and over time the sense largely remained but the exact form 'assemblement' fell out of common use in favor of 'assembly'.