What is "to be in conclave"

Conclave \Con"clave\ (? or ?; 277), n. [F., fr. L. conclave a room that may locked up; con- + clavis key. See Clavicle.]

1. The set of apartments within which the cardinals of the Roman Catholic Church are continuously secluded while engaged in choosing a pope.

2. The body of cardinals shut up in the conclave for the election of a pope; hence, the body of cardinals.

   It was said a cardinal, by reason of his apparent likelihood to step into St. Peter's chair, that in two conclaves he went in pope and came out again cardinal.
   --South.

3. A private meeting; a close or secret assembly.

   The verdicts pronounced by this conclave (Johnson's Club) on new books, were speedily known over all London.
   --Macaulay.

   To be in conclave, to be engaged in a secret meeting; -- said of several, or a considerable number of, persons.