Source : WordNet®

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"