Source : Webster's Revised Unabridged Dictionary (1913)

Know-all \Know"-all`\, n.
   One who knows everything; hence, one who makes pretension to
   great knowledge; a wiseacre; -- usually ironical. [Colloq. or
   R.]

Source : WordNet®

know-all
     n : someone who thinks he knows everything and refuses to accept
         advice or information from others [syn: {know-it-all}]