[n] having the function of uniting a group of similar things; "the Democratic Party is an umbrella for many liberal groups"; "under the umbrella of capitalism"
[n] a formation of military planes maintained over ground operations or targets; "an air umbrella over England"
[n] a lightweight handheld collapsible canopy
[adj] covering or applying simultaneously to a number of similar items or elements or groups; "an umbrella organization"; "umbrella insurance coverage"