0 past simple and past participle of mutter
1 to speak quietly and in a low voice that is not easy to hear, often when you are worried or complaining about something:
One guest at the crowded reception was heard to mutter "It's like the Black Hole of Calcutta in here."
She was muttering curses as she fumbled for the light switch.
To date, we have muttered good-will noises but have not delivered.
He muttered that we did not ask him.
I think that he muttered something about my having missed out the ethnic minorities.
I have pointed out before that we must not have muttered seated interventions.
A couple of muttered protests in 13 years is not sufficient and there will have to be a deep investigation.