The Collaborative International Dictionary of English v.0.48:

Backhanded \Back"hand`ed\, a.
   1. With the hand turned backward; as, a backhanded blow.
      [1913 Webster]

   2. Indirect; awkward; insincere; sarcastic; as, a backhanded
      compliment.
      [1913 Webster]

   3. Turned back, or inclining to the left; as, backhanded
      letters.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

backhanded \back"hand`ed\, a. & adv. (Sport)
   Stroked with a backhand[2]; as, a backhanded drive.
   [PJC]

WordNet (r) 3.0 (2006):

backhanded
    adj 1: (of racket strokes) made across the body with back of
           hand facing direction of stroke [syn: backhand(a),
           backhanded] [ant: forehand(a), forehanded]
    2: roundabout or ambiguous; "attacks from that source amounted
       to a backhanded compliment to his integrity"; "a backhanded
       and dishonest way of reaching his goal"

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "backhanded":
   O-shaped, abusive, ambagious, atrocious, backhand, calumnious,
   circuitous, circular, contumelious, deflectional, degrading,
   deviant, deviating, deviative, devious, digressive, discursive,
   divagational, divergent, excursive, helical, humiliating, indirect,
   insolent, insulting, left-handed, meandering, oblique, offensive,
   orbital, out-of-the-way, outrageous, rotary, round, roundabout,
   scurrile, scurrilous, side, sidelong, sinister, sinistral, spiral,
   unspeakable