umbrella

noun

• 1a device consisting of a circular canopy of cloth on a folding metal frame supported by a central rod, used as protection against rain.

• 2a protecting force or influence:Europe sought a measure of independence from the US defence umbrella
• a screen of fighter aircraft or anti-aircraft artillery.

• 3 [usually as modifier] a thing that includes or contains many different elements or parts:the umbrella body for more than 100 training organizations

• 4 Zoology the gelatinous disc of a jellyfish, which it contracts and expands to move through the water.