Definitions

1. adjective

bad-tempered or irritable, often in a stubborn or unreasonable way

“My grumpy neighbor complained about the noise again.”

2. noun

a person who is bad-tempered or irritable, especially in a stubborn or unreasonable way

“The grumpy old man walked out of the room in a huff.”

3. adverb

in a grumpy manner

“He grumpily got out of bed on a Sunday morning.”