Source : Webster's Revised Unabridged Dictionary (1913)

Hangdog \Hang"dog`\, n.
   A base, degraded person; a sneak; a gallows bird.

Hangdog \Hang"dog`\, a.
   Low; sneaking; ashamed.

         The poor colonel went out of the room with a hangdog
         look.                                    --Thackeray.

Source : WordNet®

hangdog
     adj 1: showing a sense of guilt; "a guilty look"; "the hangdog and
            shamefaced air of the retreating enemy"- Eric
            Linklater [syn: {guilty}, {shamefaced}, {shamed}]
     2: frightened into submission or compliance [syn: {browbeaten},
         {bullied}, {cowed}, {intimidated}]