murmur murmur /ˈmɝːmɝ/

noun

1. () A low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech  ( murmuration , mussitation , mutter , murmur , murmuring , muttering )
   a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech
   
2. () A schwa that is incidental to the pronunciation of a consonant  ( murmur vowel , murmur )
   a schwa that is incidental to the pronunciation of a consonant
   
3. A complaint uttered in a low and indistinct tone  ( grumble , murmur , murmuring , grumbling , mutter , muttering )
   a complaint uttered in a low and indistinct tone
   
4. An abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves  ( cardiac murmur , heart murmur , murmur )
   an abnormal sound of the heart; sometimes a sign of abnormal function of the heart valves
   

verb

1. () Speak softly or indistinctly  ( murmur )
   speak softly or indistinctly
    She murmured softly to the baby in her arms
   She murmured softly to the baby in her arms
   
2. Make complaining remarks or noises under one's breath  ( croak , gnarl [Archaic] , murmur , grumble , mutter , chunter [Informal, British] )
   make complaining remarks or noises under one's breath
    She grumbles when she feels overworked
   she grumbles when she feels overworked