Definition of 'co-ed'. co-ed. Word forms: plural co-eds regional note: in AM, usually use coed. 1. adjective. A co-ed school or college is the same as a co-educational school or college. He was educated at a co-ed comprehensive school. 2. countable noun. A co-ed is a female student at a co-educational college or university. ...two University of Florida coeds. A co-ed sports facility or sporting activity is one that both males and females use or take part in at the same time. You have a choice of co-ed or single-sex swimming exercise classes.