tremulant

adj

1. Trembling, tremulous.

   “The night air wrapped them warmly, and the balm of the little breezes that stirred the foliage around them was the smell of damask roses from the garden. . . . She stood by the bench, one hand resting on it; she stood all in the tremulant shadow.”

   “Lightning exploded through the sky, followed quickly by a tremulant clap of thunder.”

   “[S]he continued in a throaty, yet tremulant voice, punctuating her words with a shy, small smile.”

noun

1. A mechanical component of a musical organ, designed to add vibration to the sounds produced by the instrument.

   “The tremulant is a small apparatus that gives to the tone of any department of an organ to which it may be applied a waving or undulating effect.”

   “The tremulant intentionally disturbs the stability of the wind in order to produce a desirable musical oscillation.”