Real Dictionary

umbrella
Umbrella is used to refer to a single group or description that includes a lot of different organizations or ideas.
countable noun: An umbrella is an object which you use to protect yourself from the rain or hot sun. It consists of a long stick with a folding frame covered in cloth.

umbrella in American English
a screen or shade, usually of cloth stretched over a folding radial frame, carried for protection against the rain or sun
adjective: shaped like or intended to perform the function of an umbrella
noun: a light, small, portable, usually circular cover for protection from rain or sun, consisting of a fabric held on a collapsible frame of thin ribs radiating from the top of a carrying stick or handle

umbrella in British English
noun: a portable device used for protection against rain, snow, etc, and consisting of a light canopy supported on a collapsible metal frame mounted on a central rod
noun: an umbrella