ETYM Italian Cf. Tremulous.
1. Vocal vibrato especially an excessive or poorly controlled one.
2. (Music) A tremulous effect produced by rapid repetition of a single tone or rapid alternation of two tones.
In music, a rapidly pulsating tremor on one note, created by rapid movement of the bow on a stringed instrument, or shake of the voice. A buzzing tremolo produced by brass instruments is called flatterzunge (“flutter-tongue”).
The effect is exploited to picturesque effect in Rimsky-Korsakov’s ‘Flight of the Bumble-Bee’ interlude from the opera The Legend of Tsar Saltan 1900.