erode

badly, deeply, seriously, severely

Years of neglect had deeply eroded the old stone bridge until it became unsafe for traffic.

gradually, slowly

Years of heavy traffic gradually eroded the surface of the old stone steps.

steadily

Confidence in the government has steadily eroded since the scandal became public.

away

The cliff face has slowly eroded away, leaving dangerous gaps in the seafront path.

threaten to

Repeated criticism threatens to erode her confidence in her own abilities.