n. 1. A device for protection from the weather consisting of a collapsible, usually circular canopy mounted on a central rod. 2. a. Something shaped like an umbrella: the umbrella of a mushroom. b. The gelatinous, rounded mass that makes up the major part of the medusa stage of most jellyfish and certain other cnidarians. 3. a. Something that covers or protects: The professors were criticized for their reactionary views, but they were protected under the umbrella of academic freedom. b. Air cover, especially during a military operation. [Italian ombrella, from Late Latin umbrella, alteration (influenced by umbra, shade) of Latin umbella, parasol; see UMBEL.] um·brella·less adj. |
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