'assignment-based' originates from Modern English as a compound of the noun 'assignment' and the adjective 'based'. 'assignment' ultimately comes from Old French 'asignement' (see below), and 'based' derives from 'base'.

'assignment' changed from Latin 'assignare' (to mark out, appoint) to Old French 'asignement' and then to Middle/Modern English 'assignment'. 'base' came from Old French 'base' and Latin/Greek 'basis'; the adjective 'based' developed in Modern English and the compound 'assignment-based' formed by combining these elements.

Initially, 'assignment' meant the action or act of assigning and 'base' meant a foundation; combined, the phrase originally had a literal sense of 'having a foundation in an assignment' and has come to mean 'structured or evaluated according to assignments' in contemporary usage.