Mumble

1. v. t. To suppress, or utter imperfectly.
2. v. To speak with the lips partly closed, so as to render the sounds inarticulate and imperfect; to utter words in a grumbling indistinct manner, indicating discontent or displeasure; to mutter.
3. v. To chew something gently with closed lips.
4. v. t. To utter with a low, inarticulate voice.
5. v. t. To chew or bite gently, as one without teeth.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.