trill / tril/ • n. a quavering or vibratory sound, esp. a rapid alternation of sung or played notes: they heard the muffled trill of the telephone the caged bird launched into a piercing trill. ∎  the pronunciation of a consonant, esp. r, with rapid vibration of the tongue against the hard or soft palate or the uvula.• v. [intr.] produce a quavering or warbling sound: a skylark was trilling overhead | [with direct speech] “Coming sir,” they both trilled. ∎  [tr.] sing (a note or song) with a warbling or quavering sound: trilling a love ballad, she led him to her chair. ∎  [tr.] pronounce (a consonant) by rapid vibration of the tongue against the hard or soft palate or the uvula.

trill (shake). Ornament comprising rapid alternation of main note and note above, normally slurred, and assoc. with cadences. Occurs instrumentally and vocally. Is indicated by tr    and  . Wavy line often indicates length of trill.

trill tremulous utterance of a note XVII; vibration of tongue, etc. in pronouncing a consonant XIX. — It. trillo, †triglio.
So trill vb. XVII. — It. trillare.