To utter words, especially complaints or angry expressions, indistinctly or with a low voice and lips partly closed; to say under one's breath.
To speak softly and incoherently, or with imperfect articulations.
To make a sound with a low, rumbling noise.
A repressed or obscure utterance; an instance of muttering.
Peas.
To assert or promote one's opinion; to make one's thoughts known.