1. most bad-tempered, irritable, or complaining
Usage: superlative form of grouchy

Examples

• My grandfather is always grouchiest in the morning before his coffee.
• She becomes the grouchiest person when she’s hungry.
• The grouchiest customer complained about everything in the store.
• He’s at his grouchiest when he hasn’t had enough sleep.
• The grouchiest teacher in school actually has a kind heart.
• Even the grouchiest neighbor smiled at the children’s performance.