The Collaborative International Dictionary of English v.0.48:

Dispersion \Dis*per"sion\, n. [CF. F. dispersion.]
   1. The act or process of scattering or dispersing, or the
      state of being scattered or separated; as, the Jews in
      their dispersion retained their rites and ceremonies; a
      great dispersion of the human family took place at the
      building of Babel.
      [1913 Webster]

            The days of your slaughter and of your dispersions
            are accomplished.                     --Jer. xxv.
                                                  34.
      [1913 Webster]

   2. (Opt.) The separation of light into its different colored
      rays, arising from their different refrangibilities.
      [1913 Webster]

   Dispersion of the optic axes (Crystallog.), the separation
      of the optic axes in biaxial crystals, due to the fact
      that the axial angle has different values for the
      different colors of the spectrum.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dispersion
    n 1: spreading widely or driving off [syn: dispersion,
         scattering]
    2: the spatial or geographic property of being scattered about
       over a range, area, or volume; "worldwide in distribution";
       "the distribution of nerve fibers"; "in complementary
       distribution" [syn: distribution, dispersion] [ant:
       compactness, concentration, denseness, density,
       tightness]
    3: the act of dispersing or diffusing something; "the dispersion
       of the troops"; "the diffusion of knowledge" [syn:
       dispersion, dispersal, dissemination, diffusion]

Moby Thesaurus II by Grady Ward, 1.0:

112 Moby Thesaurus words for "dispersion":
   addition, adjunct, administration, aggrandizement, aloofness,
   ampliation, amplification, anarchy, augmentation, blackout,
   blocking, breakup, broadening, chaos, confusion, crescendo,
   deactivation, deflection, deflexure, dematerialization,
   demobilization, departure, deployment, detachment, diaspora,
   diffraction, diffusion, disappearance, disappearing, disbandment,
   disbursal, disbursement, discontinuity, discreteness,
   disintegration, disjunction, dislocation, dismissal, disorder,
   disorganization, dispensation, dispersal, disposal, disposition,
   dissipation, dissolution, dissolving, distortion, distribution,
   dole, doling, doling out, eclipse, elimination, emanation,
   enlargement, entropy, erasure, evanescence, evaporation, expansion,
   extension, extinction, fadeaway, fadeout, fading, fanning out,
   flare, flection, flexure, giving out, going, hiking, incoherence,
   inconsistency, increase, issuance, magnification, melting,
   nonadhesion, noncohesion, occultation, parting, passing,
   passing around, paying out, radiance, radiation, radius, raising,
   ray, refraction, release, scatter, scattering, separateness,
   separation, skewness, splay, split-up, spoke, spread, spreading,
   torsion, unadherence, unadhesiveness, untenacity, upping,
   vanishing, vanishing point, widening, wipe



Easton's 1897 Bible Dictionary:

Dispersion
   (Gr. diaspora, "scattered," James 1:1; 1 Pet. 1:1) of the Jews.
   At various times, and from the operation of divers causes, the
   Jews were separated and scattered into foreign countries "to the
   outmost parts of heaven" (Deut. 30:4).

     (1.) Many were dispersed over Assyria, Media, Babylonia, and
   Persia, descendants of those who had been transported thither by
   the Exile. The ten tribes, after existing as a separate kingdom
   for two hundred and fifty-five years, were carried captive (B.C.
   721) by Shalmaneser (or Sargon), king of Assyria. They never
   returned to their own land as a distinct people, although many
   individuals from among these tribes, there can be no doubt,
   joined with the bands that returned from Babylon on the
   proclamation of Cyrus.

     (2.) Many Jews migrated to Egypt and took up their abode
   there. This migration began in the days of Solomon (2 Kings
   18:21, 24; Isa. 30:7). Alexander the Great placed a large number
   of Jews in Alexandria, which he had founded, and conferred on
   them equal rights with the Egyptians. Ptolemy Philadelphus, it
   is said, caused the Jewish Scriptures to be translated into
   Greek (the work began B.C. 284), for the use of the Alexandrian
   Jews. The Jews in Egypt continued for many ages to exercise a
   powerful influence on the public interests of that country. From
   Egypt they spread along the coast of Africa to Cyrene (Acts
   2:10) and to Ethiopia (8:27).

     (3.) After the time of Seleucus Nicator (B.C. 280), one of the
   captains of Alexander the Great, large numbers of Jews migrated
   into Syria, where they enjoyed equal rights with the
   Macedonians. From Syria they found their way into Asia Minor.
   Antiochus the Great, king of Syria and Asia, removed 3,000
   families of Jews from Mesopotamia and Babylonia, and planted
   them in Phrygia and Lydia.

     (4.) From Asia Minor many Jews moved into Greece and
   Macedonia, chiefly for purposes of commerce. In the apostles'
   time they were found in considerable numbers in all the
   principal cities.

     From the time of Pompey the Great (B.C. 63) numbers of Jews
   from Palestine and Greece went to Rome, where they had a
   separate quarter of the city assigned to them. Here they enjoyed
   considerable freedom.

     Thus were the Jews everywhere scattered abroad. This, in the
   overruling providence of God, ultimately contributed in a great
   degree toward opening the way for the spread of the gospel into
   all lands.

     Dispersion, from the plain of Shinar. This was occasioned by
   the confusion of tongues at Babel (Gen. 11:9). They were
   scattered abroad "every one after his tongue, after their
   families, in their nations" (Gen. 10:5, 20,31).

     The tenth chapter of Genesis gives us an account of the
   principal nations of the earth in their migrations from the
   plain of Shinar, which was their common residence after the
   Flood. In general, it may be said that the descendants of
   Japheth were scattered over the north, those of Shem over the
   central regions, and those of Ham over the extreme south. The
   following table shows how the different families were dispersed:
   |       - Japheth
   |          - Gomer
   |              Cimmerians, Armenians
   |          - Magog
   |              Caucasians, Scythians
   |          - Madal
   |              Medes and Persian tribes
   |          - Javan
   |              - Elishah
   |                  Greeks
   |              - Tarshish
   |                  Etruscans, Romans
   |              - Chittim
   |                  Cyprians, Macedonians
   |              - Dodanim
   |                  Rhodians
   |          - Tubal
   |              Tibareni, Tartars
   |          - Mechech
   |              Moschi, Muscovites
   |          - Tiras
   |              Thracians
   |
   |       - Shem
   |          - Elam
   |              Persian tribes
   |          - Asshur
   |              Assyrian
   |          - Arphaxad
   |              - Abraham
   |                  - Isaac
   |                      - Jacob
   |                          Hebrews
   |                      - Esau
   |                          Edomites
   |                  - Ishmael
   |                      Mingled with Arab tribes
   |          - Lud
   |              Lydians
   |          - Aram
   |              Syrians
   |
   |       - Ham
   |          - Cush
   |              Ethiopans
   |          - Mizrain
   |              Egyptians
   |          - Phut
   |              Lybians, Mauritanians
   |          - Canaan
   |              Canaanites, Phoenicians