Wiktionary
drop out
vb. 1 (&lit drop out English) 2 (context idiomatic English) Prematurely and voluntarily leave (school, a race, or the like).
WordNet
drop out
v. give up in the face of defeat of lacking hope; admit defeat; "In the second round, the challenger gave up" [syn: give up, fall by the wayside, drop by the wayside, throw in, throw in the towel, quit, chuck up the sponge] [ant: enter]
leave school or an educational program prematurely; "Many students drop out because they are not prepared for our challenging program"