Source : Webster's Revised Unabridged Dictionary (1913)

Unblushing \Un*blush"ing\, a.
   Not blushing; shameless. -- {Un*blush"ing*ly}, adv.

Source : WordNet®

unblushing
     adj : feeling no shame; "a shameless imposter"; "an unblushing
           apologist for fascism" [syn: {shameless}]