scab over
To form or become covered by a scab, as of a wound. That scrape is scabbing over so it can heal, but it can't do that if you keep picking at it! You need to apply pressure to stop the blood from flowing so fast, or else the cut will never be able to scab over.
scab over
[for a wound] to form a scab. The wound soon scabbed over and the injury was well on its way to healing. I hope this shaving cut scabs over before I have to leave for work.
scab over
v. To become covered by a scab: The wound scabbed over and eventually healed.