From Longman Dictionary of Contemporary Englishmumblemum‧ble /ˈmʌmbəl/ ●●○ verb [intransitive, transitive] SAYto say something too quietly or not clearly enough, so that other people cannot understand you → mutter He bumped into someone and mumbled an apology. Stop mumbling!mumble to yourself A woman on the corner was mumbling to herself.► see thesaurus at say —mumble noun [countable]→ See Verb table
Examples from the Corpus
mumble• That smell of oil and candles and that light from a distant window and him on his knees, mumbling.• Stop mumbling!• Across the room the old woman stirred and mumbled.• Again, Robbie complied, mumbling a bit under his breath as he moved the octopus over to the doll.• He mumbled a few words and lost consciousness.• Kaye could only mumble an apology.• An old man sat on the curb, mumbling and laughing to himself.• Laverne shakes his head mumbling away his worries.• He kept to his seat and giggled, mumbled, fiddled.• Don't mumble -- I can't hear what you're saying.• He mumbled some apology and sat next to the priest.• He looked embarrassed, and mumbled something about being sorry.• She mumbled something and Dove asked her to speak up.• He mumbled something I didn't hear.• All I could do was mumble that I regretted I hadn't taken my degree.• He entertained himself for long stretches with trucks and cars, mumbling to himself as he crashed them together.mumble to yourself• It revealed, at the foot of the bed, a fat man taking off his trousers and mumbling to himself.• He entertained himself for long stretches with trucks and cars, mumbling to himself as he crashed them together.• Yo mumbles to herself at the windows outlining her hairline with a contemplative index finger.• Another hundred yards, down again, mumbling to himself in delirium.• The coroner woke like a child, mumbling to himself, wondering where he was.Origin mumble (1300-1400) From the sound 