Coed

coed 

short for coeducation, meaning schools that have a mix of men and women attending them.

coed 

A woman attending college, historically a school that would have been all male.

coed 

[modern] A female university student.

coed 

In porn, a coed is a university student type, often used to describe girls that are no longer teen but are still "youthful". A term to cover the space between say 20 and 25 years of age.

In porn, the progression is generally teen, coed, babe, hot wife, MILF, mature, then granny.