The word "scratch" generally refers to making a mark or a small cut on a surface by scraping it with a sharp object or your fingernail. It can also mean to remove something by scraping, such as scratching off an irritation on the skin. Additionally, in a more abstract sense, "scratch" can mean to cancel or get rid of something, as in "scratch that idea."
The word "scratch" comes from Middle English "scracchen," which is derived from the Old Norse word "skrækkja," meaning "to scratch," and further traces its roots back to the Proto-Germanic "*skrakō," meaning "to scratch or scrape."