conclave

Short definition from Wiktionary

Noun

1. 1
   The set of apartments in which cardinals are secluded while the process to elect a pope takes place.
2. 2
   A group of cardinals assembled to elect a new pope.
3. 3
   A group of cardinals assembled to elect a new pope: The cardinals of the Roman Catholic Church collectively.
4. 4
   A closed assembly at which cardinals elect a pope.
5. 5
   A closed assembly at which cardinals elect a pope: A closed, private, or secret meeting, especially one of an ecclesiastical nature.
6. 6
   A private chamber or room.

Verb

1. 1
   To participate in a closed, private, or secret meeting.
2. 2
   Of a cardinal: to attend a closed assembly to elect a pope.