verb
ADVERB
▪ incoherently
▪ quietly , softly
▪ quickly
▪ sleepily
▪ angrily , bitterly
▪ sarcastically
PREPOSITION
▪ about
▪
I couldn't understand what he was mumbling about.
▪ into
▪
She ~d something into her pillow.
▪ to
▪
George ~d incoherently to himself.
Mumble is used with these nouns as the object: ↑ apology , ↑ excuse , ↑ reply , ↑ word