Murmur definition

(1) A schwa that is incidental to the pronunciation of a consonant

(2) A complaint uttered in a low and indistinct tone

(3) A low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech

(4) An abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves

(5) Make complaining remarks or noises under one's breath

"She grumbles when she feels overworked"

(6) Speak softly or indistinctly

"She murmured softly to the baby in her arms"