The Collaborative International Dictionary of English v.0.48:

co-ed \co-ed\ n.
   a female student at a coeducational college or university.

   Syn: college girl.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

co-ed \co-ed\ adj.
   having both female and male students; -- of a school.

   Syn: coeducational.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

co-ed
    adj 1: attended by members of both sexes [syn: co-ed,
           coeducational]
    n 1: a female student at a coeducational college or university
         [syn: co-ed, college girl]