To tremble; to vibrate; to shake.
Especially, to shake the voice; to utter or form sound with rapid or tremulous vibrations, as in singing; also, to trill on a musical instrument
To utter with quavers.
A shake, or rapid and tremulous vibration, of the voice, or of an instrument of music.
a tremulous sound
sing or play with trills, alternating with the half note above or below