1. a pure tone.

2. a sound that has pitch.

3. in linguistics, a phonetic variable along the dimension of pitch. In a tonal language, such as Mandarin or Thai, tone has a phonemic function (see phoneme) in that differences in tone are sufficient to mark a distinction between words that are otherwise pronounced identically. In English, tone is an important suprasegmental feature of speech, with different patterns of intonation serving to distinguish different types of utterance, such as statements and questions. —tonal adj.