Having a hard exterior, or a short, rough manner, though kind at heart; snappish; peevish; surly.

brusque and surly and forbidding; "crusty remarks"; "a crusty old man"; "his curmudgeonly temper"; "gruff manner"; "a gruff reply"

Having the nature of crust; pertaining to a hard covering; as, a crusty coat; a crusty surface or substance.

Aggregate of a crust coating on a rock or mineral.

having a hardened crust as a covering