Muffle/ˈmʌfl/ Definition 1 of 2Pro Tip 1/3Diminished Clarity Muffling affects sound quality, often making words difficult to understand. During the play, the actor's lines were muffled by the thick curtains. Pro Tip 2/3Intentional Act Muffling is usually deliberate, such as to avoid being overheard. He muffled his phone's ringtone in the library. Pro Tip 3/3Partial Silence Muffling reduces noise but does not eliminate it entirely. She muffled the alarm clock's sound with a pillow.