1 : to make (a sound) quieter
They tried to muffle the noise.
to decrease the noise made by (something)
muffle [=suppress] a cough
I could hear their muffled voices from the next room.
a muffled cough
2 chiefly British : to wrap or cover (someone or something) in clothing or cloth for warmth or protection
She was muffled (up) in a huge overcoat.