noun repressed or obscure utterance.
2. mutter ·vi to sound with a low, rumbling noise.
3. mutter ·vt to utter with imperfect articulations, or with a low voice; as, to mutter threats.
4. mutter ·vi to utter words indistinctly or with a low voice and lips partly closed; ·esp., to utter indistinct complaints or angry expressions; to grumble; to growl.