Noah Webster
Quaver
QUA'VER, verb intransitive
1. To shake the voice; to utter or form sound with rapid vibrations, as in singing; to sing with tremulous modulations of voice.
2. To tremble; to vibrate.
The finger - moved with a quavering motion.
QUA'VER, noun
1. A shake or rapid vibration of the voice, or a shake on an instrument of music.
2. A note and measure of time in music, equal to half a crotchet or the eighth of a semibreve.