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

1) stumble, flounder: I had somehow blundered into a meeting of the local crime syndicate. She blundered upon the truth when she saw them together. --n. 2) mistake, error, gaffe, faux pas, slip, slip-up, howler, Colloq boo-boo, screw-up, fluff, boner, US goof, goof-up: I made a stupid blunder in telling him about the plans.