'unenrollable' originates from the prefix 'un-' meaning 'not' and the word 'enroll', which comes from Old French 'enroller', meaning 'to enroll'.

'enroll' changed from the Old French word 'enroller' and eventually became the modern English word 'enroll'.

Initially, 'enroll' meant 'to enter a name on a list', and this meaning has largely remained the same in modern usage.