Source : Webster's Revised Unabridged Dictionary (1913)

Unflinching \Un*flinch"ing\, a.
   Not flinching or shrinking; unyielding. --
   {Un*flinch"ing*ly}, adv.

Source : WordNet®

unflinching
     adj : not shrinking from danger [syn: {unblinking}, {unintimidated},
            {unshrinking}]