#1 mutter v. [mumble, maunder, mussitate] talk indistinctly; usually in a low voice. wn
#2 mutter v. [murmur, grumble, croak, gnarl] make complaining remarks or noises under one's breath; "she grumbles when she feels overworked". wn
#3 mutter n. [muttering, murmur, murmuring, murmuration, mussitation] a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech. wn
#4 mutter n. [grumble, grumbling, murmur, murmuring, muttering] a complaint uttered in a low and indistinct tone. wn
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