umbrella

(noun) a lightweight handheld collapsible canopy.

(noun) a formation of military planes maintained over ground operations or targets. Example: "An air umbrella over england."

(noun) having the function of uniting a group of similar things. Examples: "The democratic party is an umbrella for many liberal groups." "Under the umbrella of capitalism."

(adj) covering or applying simultaneously to a number of similar items or elements or groups. Examples: "An umbrella organization." "Umbrella insurance coverage."