Definition of "grump"

grump

/ɡɹʌmp/

noun
plural grumps
1. (informal) A habitually grumpy or complaining person.
2. (informal) A grumpy mood.
  Quotations
  If you're not taking Action to change the situation, either sit in a grump or Accept it.
  2004, Toby Chapman-Dawe, Passport to Performance: Raise Your Business Performance!, page 29
verb
third-person singular simple present grumps, present participle grumping, simple past and past participle grumped
1. (informal, intransitive) To complain.
  Quotations
  Grumping to himself as he made up his own bed, Bradly thought, "Have to wash that blanket; young blighter going to bed with all that mud on his feet."
  1938, Norman Lindsay, Age of Consent, 1st Australian edition, Sydney, N.S.W.: Ure Smith, published 1962, page 72
2. (informal, intransitive) To be grumpy.