mutter

To speak indistinctly in low tones.

To complain or grumble morosely.

To utter or say in low indistinct tones.

A low grumble or indistinct utterance.

To utter words in a low tone and with compressed lips, as in complaint or sullenness; murmur; grumble.

To emit a low rumbling sound.

To utter with imperfect articulation, or in a low murmuring tone.

A murmur or murmuring; sullen or veiled utterance.

To utter with imperfect articulations, or with a low voice.

Repressed or obscure utterance.