Vat ‧ i ‧ can /ˈvætɪkən/ BrE AmE noun
[ Date: 1500-1600 ; Language: Latin ; Origin: Vaticanus 'Vatican Hill' (in Rome) ]
the Vatican
a) the large ↑ palace in Rome where the Pope (=head of the Roman Catholic Church) lives and works
b) the government of the Pope:
The Vatican is taking a hard line on birth control.