Noun

• S: (n) mutter, muttering, murmur, murmuring, murmuration, mussitation (a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech)
• S: (n) grumble, grumbling, murmur, murmuring, mutter, muttering (a complaint uttered in a low and indistinct tone)
• direct hypernym / inherited hypernym / sister term
• derivationally related form
• W: (v) grumble [Related to: grumble, grumbling] (make complaining remarks or noises under one's breath) "she grumbles when she feels overworked"
• W: (v) grumble [Related to: grumble] (show one's unhappiness or critical attitude) "He scolded about anything that he thought was wrong"; "We grumbled about the increased work load"
• W: (v) murmur [Related to: murmur, murmuring] (make complaining remarks or noises under one's breath) "she grumbles when she feels overworked"
• W: (v) mutter [Related to: mutter, muttering] (make complaining remarks or noises under one's breath) "she grumbles when she feels overworked"

Verb

• S: (v) murmur (speak softly or indistinctly) "She murmured softly to the baby in her arms"
• S: (v) murmur, mutter, grumble, croak, gnarl (make complaining remarks or noises under one's breath) "she grumbles when she feels overworked"

Adjective

• S: (adj) murmuring, susurrant, whispering (making a low continuous indistinct sound) "like murmuring waves"; "susurrant voices"