The Oxford Thesaurus An A-Z Dictionary of Synonyms - quash v.

1) annul, nullify, void, declare or render null and void, invalidate, revoke, vacate, set aside, rescind, cancel, reject, throw out, reverse, overthrow, discharge, overrule: When the real culprit confessed, my conviction was quashed and I was set free. 2) suppress, subdue, quell, put down, squelch, repress, overthrow, crush, overwhelm: The rebellion was quashed by the secret police.