1. noun
    a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech
  2. noun
    a complaint uttered in a low and indistinct tone
  3. noun
    a schwa that is incidental to the pronunciation of a consonant
  4. verb
    speak softly or indistinctly; "She murmured softly to the baby in her arms"
  5. verb
    make complaining remarks or noises under one``s breath; "she grumbles when she feels overworked"
  6. noun
    an abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves