The Collaborative International Dictionary of English v.0.48:

Groggy \Grog"gy\, a.
   1. Overcome with grog; tipsy; unsteady on the legs. [Colloq.]
      [1913 Webster]

   2. Weakened in a fight so as to stagger; -- said of
      pugilists. [Cant or Slang]
      [1913 Webster]

   3. (Man.) Moving in a hobbling manner, owing to tender feet;
      -- said of a horse. --Youatt. Grogram

WordNet (r) 3.0 (2006):

groggy
    adj 1: stunned or confused and slow to react (as from blows or
           drunkenness or exhaustion) [syn: dazed, foggy,
           groggy, logy, stuporous]