Bad-tempered, easily annoyed, or complaining; ready to complain or be irritable.
From 'grouch,' probably derived from 'grudge' or related to groaning sounds of complaint. The '-y' suffix turns it into a descriptive adjective.
Oscar the Grouch on Sesame Street became so iconic that kids learned the word 'grouchy' through a puppet before many learned it from real grouchy people!
Complete word intelligence in one call. Free tier — 50 lookups/day.