The Collaborative International Dictionary of English v.0.48:

Social \So"cial\, a. [L. socialis, from socius a companion; akin
   to sequi to follow: cf. F. social. See Sue to follow.]
   1. Of or pertaining to society; relating to men living in
      society, or to the public as an aggregate body; as, social
      interest or concerns; social pleasure; social benefits;
      social happiness; social duties. "Social phenomena." --J.
      S. Mill.
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   2. Ready or disposed to mix in friendly converse;
      companionable; sociable; as, a social person.
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   3. Consisting in union or mutual intercourse.
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            Best with thyself accompanied, seek'st not
            Social communication.                 --Milton.
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   4. (Bot.) Naturally growing in groups or masses; -- said of
      many individual plants of the same species.
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   5. (Zool.)
      (a) Living in communities consisting of males, females,
          and neuters, as do ants and most bees.
      (b) Forming compound groups or colonies by budding from
          basal processes or stolons; as, the social ascidians.
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   Social science, the science of all that relates to the
      social condition, the relations and institutions which are
      involved in man's existence and his well-being as a member
      of an organized community; sociology. It concerns itself
      with questions of the public health, education, labor,
      punishment of crime, reformation of criminals, and the
      like.

   Social whale (Zool.), the blackfish.

   The social evil, prostitution.
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   Syn: Sociable; companionable; conversible; friendly;
        familiar; communicative; convival; festive.
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WordNet (r) 3.0 (2006):

social science
    n 1: the branch of science that studies society and the
         relationships of individual within a society

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "social science":
   academic discipline, academic specialty, action, actions, activity,
   acts, address, affectation, air, applied science, area, arena, art,
   bearing, behavior, behavior pattern, behavioral norm,
   behavioral science, carriage, comportment, concern, conduct,
   culture pattern, custom, demeanor, department of knowledge,
   deportment, discipline, doing, doings, domain, field,
   field of inquiry, field of study, folkway, gestures, goings-on,
   guise, maintien, manner, manners, method, methodology, methods,
   mien, modus vivendi, motions, movements, moves, natural science,
   observable behavior, ology, pattern, poise, port, pose, posture,
   practice, praxis, presence, procedure, proceeding, province,
   pure science, science, specialty, sphere, study, style, tactics,
   technicology, technics, technology, tone, way, way of life, ways