'coed' originates from American English, specifically the phrase 'co-educational' (from 'coeducation'), where 'co-' meant 'together' and 'educate' derives from Latin 'educare' meaning 'to bring up, rear'.

'co-educational' was clipped in informal American usage to 'coed' in the early 20th century; the clipped form moved from adjective use to also function as a noun referring to a student.

Initially, it referred to 'coeducational' (the system of educating males and females together), but over time it also came to mean specifically 'a female student at a coeducational institution'.