definition of
muttering

[1] #1 muttering n. [mutter, murmur, murmuring, murmuration, mussitation] a low continuous indistinct sound; often accompanied by movement of the lips without the production of articulate speech. wn

[2] #2 muttering n. [grumble, grumbling, murmur, murmuring, mutter] a complaint uttered in a low and indistinct tone. wn