drop out in WordNet English dictionary

1. give up in the face of defeat of lacking hope; admit defeat
   "In the second round, the challenger gave up"
   drop out  give up  fall by the wayside  drop by the wayside  throw in  throw in the towel  quit  chuck up the sponge 
   
2. leave school or an educational program prematurely
   "Many students drop out because they are not prepared for our challenging program"
   drop out 
   
3. 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"
   drop out 
   

drop out in English Wiktionary