IPA: /ˌoʊvərɪnˈroʊld/
KK: /oʊvərɪnˈroʊld/
Describing a situation where more students have signed up for a course or program than there are available spots.
The class was overenrolled, so many students had to be turned away.
Overenrolled → It is formed from "over-" (meaning excessively) and "enroll" (from Old French *enroller*, meaning to register or list). The word "overenrolled" means to have registered or listed excessively, typically referring to students in a course or program.
Think of being registered 'excessively' ('over-') in a program or class — that's what overenrolled means.