SOUND QUALITY [C, U] › the quality of a sound, especially of someone's voice: I knew by her tone of voice that she was serious. FEELING/STYLE [U, no plural] › the general feeling or style that something has: Then the director arrived and the whole tone of the meeting changed. TELEPHONE [C] › an electronic sound made by a telephone: a dialling tone/an engaged tone COLOUR [C] › one of the many types of a particular colour