Grouchiness is the mood of being in a bad temper, especially because you are tired, hungry, or have had a long day — not because something truly terrible has happened. It is the noun for that low, complaining, easily annoyed feeling. A person showing grouchiness snaps at small things, sighs, and finds fault. The word is informal and a little homely; you use it about family, classmates, yourself in the morning. It is not a medical word, and it is milder than rage. Though actually, it often says as much about the body (sleep, food, heat) as about a real grievance. People treat it as passing: the grouchiness lifts when the person has eaten or slept.