The Collaborative International Dictionary of English v.0.48:

Segregation \Seg`re*ga"tion\, n. [L. segregatio: cf. F.
   s['e]gr['e]gation.]
   1. The act of segregating, or the state of being segregated;
      separation from others; a parting.
      [1913 Webster]

   2. (Geol.) Separation from a mass, and gathering about
      centers or into cavities at hand through cohesive
      attraction or the crystallizing process.
      [1913 Webster]

WordNet (r) 3.0 (2006):

segregation
    n 1: (genetics) the separation of paired alleles during meiosis
         so that members of each pair of alleles appear in different
         gametes
    2: a social system that provides separate facilities for
       minority groups [syn: segregation, separatism]
    3: the act of segregating or sequestering; "sequestration of the
       jury" [syn: segregation, sequestration] [ant:
       desegregation, integrating, integration]

Moby Thesaurus II by Grady Ward, 1.0:

112 Moby Thesaurus words for "segregation":
   Jim Crow, Jim Crow law, alien, alteration, analysis, anatomization,
   anti-Semitism, apartheid, apartness, atomization, black power,
   black supremacy, change, chauvinism, class consciousness,
   class distinction, class hatred, class prejudice, class war,
   color bar, color line, contradistinction, cordon, cordon sanitaire,
   cordoning off, demarcation, desynonymization, detachment,
   differencing, differentiation, discrimination, disequalization,
   disjunction, distinction, distinctiveness, distinguishment,
   diversification, division, ethnocentrism, exclusiveness, fascism,
   foreigner, hairsplitting, individualization, individuation,
   insularity, insulation, isolation, isolationism, know-nothingism,
   male chauvinist, microscopic distinction, minority prejudice,
   modification, narrowness, nice distinction, nuance, out-group,
   outcast, outsider, parochialism, particularization,
   persona non grata, personalization, privacy, privatism,
   privatization, quarantine, quarantine flag, race hatred,
   race prejudice, race snobbery, racial discrimination,
   racial segregation, racialism, racism, recess, reclusion,
   red-baiting, retirement, retreat, rustication, sanitary cordon,
   seclusion, secrecy, separateness, separation, separatism,
   sequestration, severalization, severance, sex discrimination,
   sexism, shade of difference, snobbishness, social barrier,
   social discrimination, specialization, splendid isolation,
   stranger, subtle distinction, superpatriotism, tightness,
   trichoschistism, ultranationalism, variation, white power,
   white supremacy, withdrawal, xenophobia, yellow flag,
   yellow jack