Source : Webster's Revised Unabridged Dictionary (1913)

Pitfall \Pit"fall`\, n.
   A pit deceitfully covered to entrap wild beasts or men; a
   trap of any kind. --Sir T. North.

Source : WordNet®

pitfall
     n 1: an unforeseen or unexpected or surprising difficulty [syn: {booby
          trap}]
     2: a trap in the form of a concealed hole [syn: {pit}]