waver

verb (used without object)

1. to sway to and fro; flutter: Foliage wavers in the breeze.
2. to flicker or quiver, as light: A distant beam wavered and then disappeared.
3. become unsteady; begin to fail or give way: When she heard the news her courage wavered.
4. to shake or tremble, as the hands or voice: Her voice wavered.
5. to feel or show doubt, indecision, etc.; vacillate: He wavered in his determination.
6. (of things) to fluctuate or vary: Prices wavered.
7. to totter or reel: The earth quaked and the tower wavered.