to tremble or shake and be unsteady, usually a sign of strong emotion or nervousness, used to describe someone's voice;
e.g. Her voice began to quaver and she tried not to cry.
(noun)
a trembling or shaking quality to a sound, especially of a person's voice;
e.g. They heard a quaver in his voice, which let them know that he was nervous.
(noun)
(British) a note in music that represents one-eighth of a whole note or half of a quarter note in time value, or the symbol representing such a note in written notation;
e.g. You should play this quaver louder than the other notes.