What it means

1. verb give up in the face of defeat of lacking hope
   “In the second round, the challenger gave up”
2. verb leave school or an educational program prematurely
   “Many students drop out because they are not prepared for our challenging program”
3. 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”