- 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. - To sound with a low, rumbling noise.
3 . Mutter
[ v. t.]
- To utter with imperfect articulations, or with a low
voice; as, to mutter threats.
Meaning of 'mutter' (Princeton's WordNet)
1 . mutter
[ v]
Meaning (1): - make complaining remarks or noises under one's breath