quaver

Short definition from Wiktionary

Noun

1. 1
   A trembling shake.
2. 2
   A trembling of the voice, as in speaking or singing.
3. 3
   an eighth note, drawn as a crotchet (quarter note) with a tail.

Verb

1. 1
   To shake in a trembling manner.
2. 2
   To use the voice in a trembling manner, as in speaking or singing.
3. 3
   To utter quaveringly.