conclave(n = noun.group) - a confidential or secret meeting;
is a kind of group meeting, meeting

1.  The set of apartments within which the cardinals of the Roman Catholic Church are continuously secluded while engaged in choosing a pope. [1913 Webster]

2.  The body of cardinals shut up in the conclave for the election of a pope; hence, the body of cardinals. [1913 Webster]
"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." [1913 Webster]

3.  A private meeting; a close or secret assembly. [1913 Webster]
"The verdicts pronounced by this conclave (Johnson's Club) on new books, were speedily known over all London." [1913 Webster]

conclave, n.
1 a private meeting.
2 RC Ch. a the assembly of cardinals for the election of a pope. b the meeting-place for a conclave.

Etymology:
ME f. OF f. L conclave lockable room (as com-, clavis key)

N  assemblage, collection, collocation, colligation, compilation, levy, gathering, ingathering, muster, attroupement, team, concourse, conflux, congregation, contesseration, convergence, meeting, levee, reunion, drawing room, at home, conversazione, assembly, congress, convention, conventicle, gemote, conclave, posse, posse comitatus, Noah's ark, miscellany, collectanea, museum, menagerie, museology, crowd, throng, group, flood, rush, deluge, rabble, mob, press, crush, cohue, horde, body, tribe, crew, gang, knot, squad, band, party, swarm, shoal, school, covey, flock, herd, drove, atajo, bunch, drive, force, mulada, remuda, roundup, array, bevy, galaxy, corps, company, troop, troupe, task force, army, regiment, host, populousness, clan, brotherhood, fraternity, sorority, association, volley, shower, storm, cloud, group, cluster, Pleiades, clump, pencil, set, batch, lot, pack, budget, assortment, bunch, parcel, packet, package, bundle, fascine, fasces, bale, seron, seroon, fagot, wisp, truss, tuft, shock, rick, fardel, stack, sheaf, haycock, fascicle, fascicule, fasciculus, gavel, hattock, stook, accumulation, congeries, heap, lump, pile, rouleau, tissue, mass, pyramid, bing, drift, snowball, snowdrift, acervation, cumulation, glomeration, agglomeration, conglobation, conglomeration, conglomerate, coacervate, coacervation, coagmentation, aggregation, concentration, congestion, omnium gaterum, spicilegium, black hole of Calcutta, quantity, collector, gatherer, whip, whipper in, assembled, closely packed, dense, serried, crowded to suffocation, teeming, swarming, populous, as thick as hops, all of a heap, fasciculated cumulative, the plot thickens, acervatim, tibi seris tibi metis.

N  council, committee, subcommittee, comitia, court, chamber, cabinet, board, bench, staff, senate, senatus, parliament, chamber of deputies, directory, reichsrath, rigsdag, cortes, storthing, witenagemote, junta, divan, musnud, sanhedrim, classis, Amphictyonic council, duma, house of representatives, legislative assembly, legislative council, riksdag, volksraad, witan, caput, consistory, chapter, syndicate, court of appeal, board of control, board of works, vestry, county council, local board, audience chamber, council chamber, state chamber, cabinet council, privy council, cockpit, convocation, synod, congress, convention, diet, states-general, assembly, caucus, conclave, clique, conventicle, meeting, sitting, seance, conference, convention, exhibition, session, palaver, pourparler, durbar, house, quorum, council fire, powwow, primary, meeting, assemblage, member, senator, member of parliament, M, P, councilor, representative of the people, assemblyman, congressman, councilman, councilwoman, alderman, freeholder, senatorial, curule, congressional, parliamentary, legislative, law-making, regulatory, deliberative.

N  church, churchdom, ministry, apostleship, priesthood, prelacy, hierarch, church government, christendom, pale of the church, clericalism, sacerdotalism, episcopalianism, ultramontanism, theocracy, ecclesiology, ecclesiologist, priestcraft, odium theologicum, monachism, monachy, monasticism, monkhood, pontificate, primacy, archbishopric, archiepiscopacy, prelacy, bishopric, bishopdom, episcopate, episcopacy, see, diocese, deanery, stall, canonry, canonicate, prebend, prebendaryship, benefice, incumbency, glebe, advowson, living, cure, rectorship, vicariate, vicarship, deaconry, deaconship, curacy, chaplain, chaplaincy, chaplainship, cardinalate, cardinalship, abbacy, presbytery, holy orders, ordination, institution, consecration, induction, reading in, preferment, translation, presentation, popedom, the Vatican, the apostolic see, religious sects, council, conclave, convocation, synod, consistory, chapter, vestry, sanhedrim, conge d'elire, ecclesiastical courts, consistorial court, court of Arches, ecclesiastical, ecclesiological, clerical, sacerdotal, priestly, prelatical, pastoral, ministerial, capitular, theocratic, hierarchical, archiepiscopal, episcopal, episcopalian, canonical, monastic, monachal, monkish, abbatial, abbatical, Anglican, pontifical, papal, apostolic, Roman, Popish, ultramontane, priest-ridden.