Webster's Revised Unabridged Dictionary · 1913

Quaver

Quaver , intransitive verb

[Old English quaven to shake, to tremble; compare LG. quabbeln to shake, to be soft, of fat substances, quabbe a fat lump of flesh, a dewlap, Dutch kwabbe, and English quiver, v.]

1.
To tremble; to vibrate; to shake. — Sir I. Newton
2.
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

Quaver , transitive verb

To utter with quavers.
We shall hear her quavering them... to some sprightly airs of the opera. — Addison

Quaver , noun

1.
A shake, or rapid and tremulous vibration, of the voice, or of an instrument of music.
2.
(Music) An eighth note. See Eighth.