noun

1. a screen or shade, usually of cloth stretched over a folding radial frame, carried for protection against the rain or sun
2. something suggestive of this; specif.,
   1. the body of a jellyfish
   2. any comprehensive, protective organization, alliance, strategy, or device the umbrella of insurance
   3. a force of military aircraft sent up to screen ground or naval forces air umbrella

Etymology: It ombrella < LL umbrella (altered by assoc. with L umbra, shade) < L umbella, parasol, dim. of umbra, shade