Definition of "tremolo"

tremolo

/ˈtrɛmələʊ/

noun
countable and uncountable, plural tremolos
1. (music) A rapid repetition of the same note, or an alternation between two or more notes. It can also be intended to mean a rapid and repetitive variation in pitch for the duration of a note. It is notated by a strong diagonal bar across the note stem, or a detached bar for a set of notes (or stemless notes).
  Quotations
  It commenced with a slow crescendo, so irresistibly lugubrious that two of our dogs at once raised their heads and swelled their voices into a responsive tremolo, which may have been heard and appreciated by their distant relatives.
  1880, Felix Leopold Oswald, Summerland Sketches, page 57
2. (music) A variation in the volume of a note or a chord, evoking a tremor or quiver.
3. (music) The device in an organ that produces a tremolo effect.