The Collaborative International Dictionary of English v.0.48:

Outflank \Out*flank"\, v. t.
   1. (Mil.) To go beyond, or be superior to, on the flank; to
      pass around or turn the flank or flanks of.
      [1913 Webster]

   2. Hence: To outmaneuver in a competition; to bypass a
      competitor's main defenses.
      [PJC]

WordNet (r) 3.0 (2006):

outflank
    v 1: go around the flank of (an opposing army) [syn: outflank,
         go around]
    2: get the better of; "the goal was to best the competition"
       [syn: outdo, outflank, trump, best, scoop]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "outflank":
   circumvent, deceive, elude, evade, foil, frustrate, get around,
   get round, give the runaround, give the slip, go one better,
   outfigure, outgeneral, outguess, outmaneuver, outplay, outreach,
   outsmart, outwit, overreach, pass the buck, stonewall, victimize