trill

n. 1 quavering sound, esp. A rapid alternation of sung or played notes. 2 bird's warbling. 3 pronunciation of r with vibration of the tongue. v. 1 produce a trill. 2 warble (a song) or pronounce (r etc.) With a trill. [italian]

v. i. To flow in a small stream, or in drops rapidly succeeding each other; to trickle.