Meaning of mutter:
1.say something in a low or barely audible voice, especially in dissatisfaction or irritation."he muttered something under his breath"
sinónimos: talk under one's breath, murmur, mumble, whisper, speak in an undertone"a group of men stood muttering"
1.a barely audible utterance, especially a dissatisfied or irritated one."a little mutter of disgust"