mutter

1 to express dissatisfaction, pain, or resentment usually tiresomely a muttering group of workers Synonyms beef, bellyache, bitch, bleat, carp, caterwaul, crab, croak, fuss, gripe, grizzle, grouch, grouse, growl, grumble, grump, holler, inveigh, keen, kick, kvetch, maunder [chiefly British], moan, murmur, complain, nag, repine, scream, squawk, squeal, wail, whimper, whine, whinge [British], yammer, yawp (or yaup), yowlRelated Words object (to), protest, quarrel (with); cavil, quibble; fret, stew, worry; blubber, cry, sob; bemoan, bewail, deplore, lamentNear Antonyms accept, bear, countenance, endure, take, tolerate; applaud, cheer, commendAntonyms crow, delight, rejoice

2 to speak softly and unclearly muttering to himself under his breath Synonyms chunter [British], grunt, mouth, murmur, mumbleRelated Words babble, blab, chatter, drivel, gabble, gibber, jabber, maunder, prattle, ramble; breathe, gasp, pant, whisper; buzzNear Antonyms articulate, enunciateAntonyms speak out, speak up