WIKIPEDIA: An umbrella or parasol (also called a brolly, rainshade, sunshade, gamp or bumbershoot) is a canopy designed to protect against rain or sunlight. The term parasolusually refers to an item designed to protect from the sun; umbrella refers to a device more suited to protect from rain. Often the difference is the material; some parasols are not waterproof. Parasols are often meant to be fixed to one point and often used with patio tables or other outdoor furniture. Umbrellas are almost exclusively hand-held portable devices; however, parasols can also be hand-held. Umbrellas can be held as fashion accessories.
The word umbrella comes from the Latin word umbra, meaning shade or shadow (the Latin word, in turn, derives from the Ancient Greek ómbros). Brolly is aslang word for umbrella, used often in Britain, New Zealand, Australia, and South Africa; Bumbershoot is a fanciful Americanism from the late 19th century.