1.  concentration(n = noun.attribute) Array - the strength of a solution; number of molecules of a substance in a given volume; Array
is a kind of property
has particulars: titer, titre, hydrogen ion concentration, molal concentration, molality, m, molar concentration, molarity
Derived form verb concentrate₁

2.  concentration(n = noun.attribute) compactness, denseness, density, tightness - the spatial property of being crowded together; Array
is a kind of spacing, spatial arrangement
Antonym: distribution
Derived form verb concentrate₅

3.  concentration(n = noun.act) Array - strengthening the concentration (as of a solute in a mixture) by removing diluting material; Array
is a kind of strengthening
has particulars: pervaporation
Antonym: dilution
Derived forms verb concentrate₈, verb concentrate₇, verb concentrate₁, verb concentrate₄, verb concentrate₆

4.  concentration(n = noun.event) Array - increase in density; Array
is a kind of increase
has particulars: compaction, compression, concretion, densification, rarefaction
Derived forms verb concentrate₈, verb concentrate₇, verb concentrate₁

5.  concentration(n = noun.cognition) absorption, engrossment, immersion - complete attention; intense mental effort; Array
is a kind of attention
has particulars: centering, direction, focal point, focus, focusing, focussing, specialism, study
Derived form verb concentrate₂

6.  concentration(n = noun.act) Array - bringing together military forces; Array
is a kind of assemblage, assembly, gathering
Derived form verb concentrate₅

7.  concentration(n = noun.attribute) assiduity, assiduousness - great and constant diligence and attention; Array
is a kind of diligence, industriousness, industry
has particulars: engrossment, intentness, singleness
Derived form verb concentrate₂

1.  The act or process of concentrating; the process of becoming concentrated, or the state of being concentrated; concentration. [1913 Webster]
"Concentration of the lunar beams." [1913 Webster]
"Intense concetration of thought." [1913 Webster]

2.  The act or process of reducing the volume of a liquid, as by evaporation. [1913 Webster]
"The acid acquires a higher degree of concentration." [1913 Webster]

3.  The act or process of removing the dress of ore and of reducing the valuable part to smaller compass, as by currents of air or water. [1913 Webster]

concentration, n.
1 a the act or power of concentrating (needs to develop concentration). b an instance of this (interrupted my concentration).
2 something concentrated (a concentration of resources).
3 something brought together; a gathering.
4 the weight of substance in a given weight or volume of material.

Idiom:
concentration camp a camp for the detention of political prisoners, internees, etc., esp. in Nazi Germany.

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  centrality, centricalness, center, middle, focus, core, kernel, nucleus, nucleolus, heart, pole axis, bull's eye, nave, navel, umbilicus, backbone, marrow, pith, vertebra, vertebral column, hotbed, concentration, centralization, symmetry, center of gravity, center of pressure, center of percussion, center of oscillation, center of buoyancy, metacenter, central, centrical, middle, azygous, axial, focal, umbilical, concentric, middlemost, rachidian, spinal, vertebral, middle, midst, centrally.

N  convergence, confluence, concourse, conflux, congress, concurrence, concentration, convergency, appulse, meeting, corradiation, assemblage, resort, asymptote, converging, convergent, confluent, concurrent, centripetal, asymptotical, asymptotic, confluxible.

concentration camp, hydrogen ion concentration, molal concentration, molar concentration