1.  aggregation(n = noun.group) accumulation, assemblage, collection - several things grouped together or considered as a whole;
is a kind of group, grouping
has particulars: procession, pharmacopoeia, string, wardrobe, wardrobe, population, universe, armamentarium, art collection, backlog, battery, block, book, rule book, book, bottle collection, bunch, caboodle, lot, coin collection, collage, content, ensemble, tout ensemble, corpus, crop, tenantry, findings, flagging, flinders, pack, deal, hand, long suit, herbarium, stamp collection, statuary, sum, sum total, summation, agglomeration, gimmickry, nuclear club, agglomerate, cumulation, cumulus, heap, mound, pile, mass, combination, congregation, hit parade, judaica, kludge, library, program library, subroutine library, library, mythology, biology, biota, fauna, zoology, petting zoo, set, victoriana, category, class, family, job lot, bundle, package, packet, parcel, defence, defense, defense lawyers, defense team, prosecution, planting, signage, gaap, generally accepted accounting principles, pantheon, free world, third world, europe, asia, north america, central america, south america, oort cloud, galaxy, extragalactic nebula, galaxy, fleet, fleet, fleet, repertoire, repertory, repertoire, repertory, assortment, miscellanea, miscellany, mixed bag, mixture, motley, potpourri, salmagundi, smorgasbord, variety, batch, clutch, batch, rogue's gallery, exhibition, expo, exposition, convoy, traffic, air power, aviation, botany, flora, vegetation, jurisprudence, law, menagerie, data, information, ana, mail, post, treasure, treasure trove, trinketry, troponomy, troponymy, smithereens, nag hammadi, nag hammadi library, magi, wise men

2.  aggregation(n = noun.act) assembling, collecting, collection - the act of gathering something together;
is a kind of grouping
has particulars: agglomeration, collation, compilation, compiling, gather, gathering, bottle collection, conchology, shell collecting, coin collecting, coin collection, numismatics, numismatology, pickup, philately, stamp collecting, stamp collection, tax collection

   The act of aggregating, or the state of being aggregated; collection into a mass or sum; a collection of particulars; an aggregate. [1913 Webster]
"Each genus is made up by aggregation of species." [1913 Webster]
"A nation is not an idea only of local extent and individual momentary aggregation, but . . . of continuity, which extends in time as well as in numbers, and in space." [1913 Webster]

N  coherence, adherence, adhesion, adhesiveness, concretion accretion, conglutination, agglutination, agglomeration, aggregation, consolidation, set, cementation, sticking, soldering, connection, dependence, tenacity, toughness, stickiness, inseparability, inseparableness, bur, remora, conglomerate, concrete, cohesive, adhesive, adhering, cohering, tenacious, tough, sticky, united, unseparated, unsessile, inseparable, inextricable, infrangible, compact.

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.