murmuring

(noun) a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech. Synonyms: mutter, muttering, murmur, murmuration, mussitation.

(noun) a complaint uttered in a low and indistinct tone. Synonyms: grumble, grumbling, murmur, mutter, muttering.

(verb) speak softly or indistinctly. Synonyms: murmur. Examples: "She murmured softly to the baby in her arms."

(verb) make complaining remarks or noises under one's breath. Synonyms: murmur, mutter, grumble, croak, gnarl. Examples: "She grumbles when she feels overworked."

(adj) making a low continuous indistinct sound. Synonyms: susurrant, whispering. Examples: "Like murmuring waves." "Susurrant voices."