Tremolo \Tre"mo*lo\, n. [It. Cf. {Tremulous}.] (Mus.)
(a) The rapid reiteration of tones without any apparent
cessation, so as to produce a tremulous effect.
(b) A certain contrivance in an organ, which causes the notes
to sound with rapid pulses or beats, producing a
tremulous effect; -- called also {tremolant}, and
{tremulant}.
[1913 Webster]