mutter
n. countablen. a low, quiet sound made with your mouth, usually when you are angry or upset. It is like talking to yourself in a way that others cannot hear clearly.
n. a low, indistinct sound made with the lips and tongue, typically expressing irritation or dissatisfaction. Often used to describe the act of speaking in a way that is barely audible to others.
He gave a low mutter of frustration as the door stuck.
The crowd began a low mutter of discontent as the speaker continued to ignore their questions.
A low mutter of protest rose from the back of the room, though no one dared to voice their concerns directly to the committee members.
From Middle English muteren, moteren, of imitative origin. Compare Low German mustern, musseln (“to whisper”), German muttern (“to mutter; whisper”), Old Norse muðla (“to murmur”). Compare also Latin muttīre, mutīre.
From Hindi मटर (maṭar).