drop out has 7 distinct synonyms spread across 1 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is enter.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
give up in the face of defeat of lacking hope; admit defeat
“In the second round, the challenger gave up”
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”
leave school or an educational program prematurely
“Many students drop out because they are not prepared for our challenging program”
Synonyms, antonyms and the broader and narrower relations for drop out come from Princeton University’s WordNet. Full sources and licences.