Do you know ghouls from goblins and ghosts?
late 14c., "a flowing out of blood;" mid-15c. as "a drawing out of blood;" verbal noun formed after earlier present participle adjective (early 13c.) of bleed. Figurative use is from 1796. As a euphemism for bloody, from 1858. In U.S. history, Bleeding Kansas, in reference to the slavery disputes in that territory 1854-60, is attested from 1856, said to have been first used by the New York "Tribune."