<p><strong>Verb</strong></p><ul><li>(used with object) to sing or play with a vibratory or quavering effect.</li><li>(Phonetics) to produce (a sound) with a trill.</li><li>(of birds, insects, etc.) to sing or utter in a succession of rapidly alternating sounds.</li></ul><p><strong>Noun</strong></p><ul><li>the act or sound of trilling.</li><li>a rapid alternation of two adjacent tones; a shake.</li><li>a similar sound, or succession of sounds, uttered or made by a bird, an insect, a person laughing, etc.</li><li>(Phonetics) a sequence of repetitive, rapid, vibratory movements produced in any free articulator or membrane by a rush of air expelled from the lungs, often causing a corresponding sequence of contacts between the vibrating articulator and another organ or surface.</li></ul>