A blend of bumber (an alteration of umbr- from umbrella) and shoot (an alteration of -chute from parachute, an open parachute resembling an umbrella). First recorded in 1876 in the Chester, Pennsylvania Times. Early variants included bumbersol (with sol from parasol) and bumberell. The spelling settled on bumbershoot by the early 1900s. Identified by the OED as 'originally and chiefly U.S. slang'.