qua·ver 
(kwāvər)
(kwāvər)v. qua·vered, qua·ver·ing, qua·vers
v.intr.
1. To quiver, as from weakness; tremble.
2. To speak in a quivering voice; utter a quivering sound.
3. Music To produce a trill on an instrument or with the voice.
v.tr.
To utter or sing in a trilling voice.
n.
1. A quivering sound.
2. Music
a. A trill.
b. An eighth note.
[Middle English quaveren, probably frequentative of cwavien, quaven, to tremble.]
quaver·ing·ly adv.
quaver·y adj.