'drop out' definitions:

Definition of 'drop out'

(from WordNet)
verb
Give up in the face of defeat of lacking hope; admit defeat; "In the second round, the challenger gave up" [syn: drop out, give up, fall by the wayside, drop by the wayside, throw in, throw in the towel, quit, chuck up the sponge] [ant: enter, participate]
verb
Withdraw from established society, especially because of disillusion with conventional values; "She hasn't heard from her brother in years--he dropped out after moving to California"
verb
Leave school or an educational program prematurely; "Many students drop out because they are not prepared for our challenging program"

Synonyms of 'drop out'

From: Moby Thesaurus