muffle (v.)youdaoicibaDictYouDict
early 15c., "to cover or wrap (something) to conceal or protect," perhaps from Middle French mofler "to stuff," from Old French moufle "thick glove, muff" (compare Old French enmoufle "wrapped up"); see muff (n.). Meaning "wrap something up to deaden sound" first recorded 1761. Related: Muffled; muffling.
put-putyoudaoicibaDictYouDict
indicating the sound of a muffled internal combustion engine, 1904, imitative.