drop out (Noun) — Someone who quits school before graduation.
drop out (Noun) — Someone who withdraws from a social group or environment.
drop out (Verb) — Give up in the face of defeat of lacking hope; admit defeat. ex. "In the second round, the challenger dropped out"
drop out (Verb) — Withdraw from established society, especially because of disillusion with conventional values. ex. "She hasn't heard from her brother in years--he dropped out after moving to California"
drop out (Verb) — Leave school or an educational program prematurely. ex. "Many students drop out because they are not prepared for our challenging program"