The Collaborative International Dictionary of English v.0.48:
Know-all \Know"-all`\, n. One who knows everything; hence, one who makes pretension to great knowledge; a wiseacre; a know-it-all; -- usually ironical. [Colloq. or R.] [1913 Webster]WordNet (r) 3.0 (2006):
know-all n 1: someone who thinks he knows everything and refuses to accept advice or information from others [syn: know-it- all, know-all]