late 14c., "a flowing out of blood;" mid-15c. as "a drawing out of blood," verbal noun from bleed (v.).
early 13c., present-participle adjective from bleed (v.). Figurative use is from 1796. As a euphemism for bloody, by 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." The shell known as the bleeding tooth is attested from 1849.