'raiment' originates from Old French, specifically the word 'raiment', where the original term referred to 'clothing' or 'attire' (the exact older root is uncertain).

'raiment' entered Middle English from Old French 'raiment' (appearing also as 'rayment') and eventually remained in Modern English as the literary/archaic noun 'raiment'.

Initially, it meant 'clothing' and over time the basic meaning has remained, but the word became archaic and is now mainly literary or poetic.