umbrella

A device for protection from the weather consisting of a collapsible, usually circular canopy mounted on a central rod.

Something shaped like an umbrella.

The gelatinous, rounded mass that makes up the major part of the medusa stage of most jellyfish and certain other cnidarians.

Something that covers or protects.

Air cover, especially during a military operation.

A portable shade, screen, or canopy which opens and folds, carried in the hand for the purpose of sheltering the person from the rays of the sun or from rain.

In zoology: The gelatinous disk or swimming-bell of an acaleph, as a jellyfish, by the rhythmical contraction and expansion of which the creature swims, taken either with or without the velum.

In conchology [NL. (Lamarck, 1809).] [capitalized] A genus of tectibranchiate or pleurobranchiate gastropods; the umbrella-shells, as U. umbellata. Also Ombrella. A limpet-like tectibranchiate gastropod of the genus Umbrella or family Umbrellidæ; an umbrella-shell.