mut•terPronunciation: (mut'ur), [key]
to utter words indistinctly or in a low tone, often as if talking to oneself; murmur.
to complain murmuringly; grumble.
to make a low, rumbling sound.
to utter indistinctly or in a low tone: to mutter complaints.
the act or utterance of a person who mutters.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.