quaver

To quiver, as from weakness; tremble.

To speak in a quivering voice; utter a quivering sound.

To produce a trill on an instrument or with the voice.

To utter or sing in a trilling voice.

A quivering sound.

A trill.

An eighth note.

To have a tremulous motion; tremble; vibrate.

To sing or sound with the wavy tones of an untrained voice, or with a distinctly tremulous tone; hence, to sing, in general; also, to perform a shake or similar melodic embellishment with the voice or an instrument.