See murmurer in Webster's New World Roget's A-Z Thesaurus II
noun
A person who habitually complains or grumbles:
complainer, crab, faultfinder, grouch, growler, grumbler, grump, mutterer, whiner. (Informal) crank, griper, grouser. (Slang) bellyacher, sorehead, sourpuss. See happy
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