[1] : WordNet (r) 2.0

drop out
     v 1: 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
     2: leave school or an educational program prematurely; "many
        students drop out because they are not prepared for our
        challenging program"
see also:
give up fall by the wayside drop by the wayside throw in throw in the towel quit 
chuck up the sponge enter 

[2] : Moby Thesaurus II by Grady Ward, 1.0

52 moby thesaurus words for "drop out":
   abandon, agree to differ, agree to disagree, back out,
   be at variance, be in dissent, beg off, beg to differ,
   break bounds, break step, cry off, depart from, differ, disagree,
   disagree with, discard, discord with, dissent, dissent from,
   divide on, evacuate, forsake, go back on, jettison, jilt, leave,
   leave behind, leave flat, make waves, maroon, nonconform,
   not agree, not comply, not conform, oppose, opt out, protest,
   pull out, quit, quit cold, renege, rock the boat, say goodbye to,
   secede, stand down, take exception, take issue, take leave of,
   throw over, vacate, withdraw, withhold assent

Bail Out >> B Words
Bail Out, definition of term: Bail Out
bail+out_pag1.html

Bale Out >> B Words
Bale Out, definition of term: Bale Out
bale+out_pag1.html

Back Out >> B Words
Back Out, definition of term: Back Out
back+out_pag1.html

Ask Out >> A Words
Ask Out, definition of term: Ask Out
ask+out_pag1.html

Air Out >> A Words
Air Out, definition of term: Air Out
air+out_pag1.html

Act Out >> A Words
Act Out, definition of term: Act Out
act+out_pag1.html