waver
Definitions
To shake or tremble with a quivering motion.
To become unsteady or unreliable; to show indecision.
To flicker or be unsteady in brightness or sound.
Examples
Her voice began to waver as she recounted the difficult events of the past year.
Despite the intense pressure from his opponents, he did not waver in his commitment to the cause.
The candle flame started to waver in the drafty hallway.