The Collaborative International Dictionary of English v.0.48:

Grumpy \Grump"y\, a. [Cf. Grumble, and Grum.]
   Surly; dissatisfied; grouty. [Collog.] --Ferby.
   [1913 Webster]

WordNet (r) 3.0 (2006):

grumpy
    adj 1: annoyed and irritable [syn: crabbed, crabby, cross,
           fussy, grouchy, grumpy, bad-tempered, ill-
           tempered]