A person who complains frequently, persistently, and usually in a bad-tempered manner.
From grumble (to complain) plus the -er suffix denoting an agent or person who performs an action. This agent noun formation dates back centuries in English.
Professional grumblers are actually a documented feature of workplace culture—studies show that chronic complainers, while annoying, sometimes provide genuine value by voicing problems others ignore. The key difference: effective grumblers offer solutions, not just complaints.
Complete word intelligence in one call. Free tier — 50 lookups/day.