gate ‧ keep ‧ er /ˈɡeɪtˌkiːpə $ -ər/ BrE AmE noun [countable]
1 . someone whose job is to open and close a gate, and to allow or not allow people to go through it
2 . someone in an organization who has a lot of influence over what products the organization buys, who it buys them from etc
3 . someone in an organization who tells customers or people with questions which people in the organization should be able to help them