umbrella

um‧brel‧la [countable]

1 an object that you use to protect yourself against rain or hot sun. It consists of a circular folding frame covered in cloth [↪ parasol]:

It started to rain, so Tricia stopped to put upher umbrella.

I spent the day on the beach, lying under a beach umbrella, reading.

2

umbrella organization/group/agency etc

 an organization that includes many smaller groups

3

umbrella term/word/title etc

 a word whose meaning includes many different types of a particular thing:

District nurses, health visitors, and school nurses will come under the umbrella term 'community nursing'.

4

(come/work etc) under the umbrella of something

 to be part of a larger organization or involved in the work done by it:

The international education program came under the umbrella of the State Department.

5 the protection given by a powerful country, army, a weapons system etc:

the American nuclear umbrella over western Europe

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.