Source : Webster's Revised Unabridged Dictionary (1913)

Murmuring \Mur"mur*ing\, a. & n.
   Uttering murmurs; making low sounds; complaining. --
   {Mur"mur*ing*ly}, adv.

Murmur \Mur"mur\, v. i. [imp. & p. p. {Murmured}; p. pr. & vb.
   n. {Murmuring}.] [F. murmurer, L. murmurare, murmurari, fr.
   murmur murmur; cf. Gr.? to roar and boil, said of water, Skr.
   marmara a rustling sound; prob. of imitative origin.]
   1. To make a low continued noise, like the hum of bees, a
      stream of water, distant waves, or the wind in a forest.

            They murmured as doth a swarm of bees. --Chaucer.

   2. To utter complaints in a low, half-articulated voice; to
      feel or express dissatisfaction or discontent; to grumble;
      -- often with at or against. ``His disciples murmured at
      it.'' --John vi. 61.

            And all the children of Israel murmured against
            Moses and against Aaron.              --Num. xiv. 2.

            Neither murmur ye, as some of them also murmured.
                                                  --1 Cor. x.
                                                  10.

Source : WordNet®

murmuring
     adj : making a low continuous indistinct sound; "like murmuring
           waves"; "susurrant voices" [syn: {susurrant}, {whispering}]
     n 1: a low continuous indistinct sound; often accompanied by
          movement of the lips without the production of
          articulate speech [syn: {mutter}, {muttering}, {murmur},
           {murmuration}, {mussitation}]
     2: a complaint uttered in a low and indistinct tone [syn: {grumble},
         {grumbling}, {murmur}, {mutter}, {muttering}]