The Collaborative International Dictionary of English v.0.48:

Separation \Sep`a*ra"tion\, n. [L. separatio: cf. F.
   s['e]paration.]
   The act of separating, or the state of being separated, or
   separate. Specifically:
   (a) Chemical analysis.
   (b) Divorce.
   (c) (Steam Boilers) The operation of removing water from
       steam.
       [1913 Webster]

   Judicial separation (Law), a form of divorce; a separation
      of man and wife which has the effect of making each a
      single person for all legal purposes but without ability
      to contract a new marriage. --Mozley & W.
      [1913 Webster]

WordNet (r) 3.0 (2006):

separation
    n 1: the state of lacking unity [ant: unification, union]
    2: coming apart [syn: separation, breakup, detachment]
    3: the distance between things; "fragile items require
       separation and cushioning" [syn: interval, separation]
    4: sorting one thing from others; "the separation of wheat from
       chaff"; "the separation of mail by postal zones"
    5: the social act of separating or parting company; "the
       separation of church and state"
    6: the space where a division or parting occurs; "he hid in the
       separation between walls"
    7: the termination of employment (by resignation or dismissal)
    8: (law) the cessation of cohabitation of man and wife (either
       by mutual agreement or under a court order) [syn: legal
       separation, separation]
    9: the act of dividing or disconnecting