noun Any low, indistinct sound, like that of running water.
noun Soft indistinct speech.
A murmur arose from the audience.
noun The sound made by any condition which produces a noisy, or turbulent, flow of blood through the heart.
noun A muttered complaint or protest; the expression of dissatisfaction in a low muttering voice; any expression of complaint or discontent.
verb To grumble; to complain in a low, muttering voice, or express discontent at or against someone or something. .mw-parser-output .defdate{font-size:smaller}
verb To speak or make low, indistinguishable noise; to mumble, mutter.
I couldn't hear the words; he just murmured a lot.