Grouchy means irritable and bad-tempered, like when someone wakes up on the wrong side of the bed and everything seems to bother them. A grouchy person complains about things that wouldn't normally upset them, snaps at others over small matters, or just radiates crankiness.

You might feel grouchy when you're tired, hungry, or sick. Your normally cheerful friend might get grouchy after staying up too late, responding to friendly questions with grunts and eye rolls. Teachers sometimes notice the whole class getting grouchy right before lunch, when everyone's blood sugar drops and patience wears thin.

Being grouchy is usually temporary, unlike being mean or cruel, which can be more lasting behavior patterns. Most people don't want to be grouchy, but sometimes hunger, exhaustion, or frustration takes over. The feeling usually passes after some food, rest, or time to cool off. When you notice someone acting grouchy, it often means they need space or help with whatever's bothering them, rather than taking their mood personally.