Source : Webster's Revised Unabridged Dictionary (1913)

Crusty \Crust"y\ (-[y^]), a.
   1. Having the nature of crust; pertaining to a hard covering;
      as, a crusty coat; a crusty surface or substance.

   2. [Possibly a corruption of cursty. Cf. {Curst},
      {Curstness}.] Having a hard exterior, or a short, rough
      manner, though kind at heart; snappish; peevish; surly.

            Thou crusty batch of nature, what's the news?
                                                  --Shak.

Source : WordNet®

crusty
     adj 1: having a hardened crust as a covering [syn: {crusted}, {encrusted},
             {crustlike}]
     2: brusque and surly and forbidding; "crusty remarks"; "a
        crusty old man"; "his curmudgeonly temper"; "gruff
        manner"; "a gruff reply" [syn: {curmudgeonly}, {gruff}, {ill-humored},
         {ill-humoured}]
     [also: {crustiest}, {crustier}]