The Collaborative International Dictionary of English v.0.48:

Case \Case\, n. [F. cas, fr. L. casus, fr. cadere to fall, to
   happen. Cf. Chance.]
   1. Chance; accident; hap; opportunity. [Obs.]
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            By aventure, or sort, or cas.         --Chaucer.
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   2. That which befalls, comes, or happens; an event; an
      instance; a circumstance, or all the circumstances;
      condition; state of things; affair; as, a strange case; a
      case of injustice; the case of the Indian tribes.
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            In any case thou shalt deliver him the pledge.
                                                  --Deut. xxiv.
                                                  13.
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            If the case of the man be so with his wife. --Matt.
                                                  xix. 10.
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            And when a lady's in the case
            You know all other things give place. --Gay.
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            You think this madness but a common case. --Pope.
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            I am in case to justle a constable,   --Shak.
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   3. (Med. & Surg.) A patient under treatment; an instance of
      sickness or injury; as, ten cases of fever; also, the
      history of a disease or injury.
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            A proper remedy in hypochondriacal cases.
                                                  --Arbuthnot.
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   4. (Law) The matters of fact or conditions involved in a
      suit, as distinguished from the questions of law; a suit
      or action at law; a cause.
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            Let us consider the reason of the case, for nothing
            is law that is not reason.            --Sir John
                                                  Powell.
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            Not one case in the reports of our courts. --Steele.
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   5. (Gram.) One of the forms, or the inflections or changes of
      form, of a noun, pronoun, or adjective, which indicate its
      relation to other words, and in the aggregate constitute
      its declension; the relation which a noun or pronoun
      sustains to some other word.
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            Case is properly a falling off from the nominative
            or first state of word; the name for which, however,
            is now, by extension of its signification, applied
            also to the nominative.               --J. W. Gibbs.
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   Note: Cases other than the nominative are oblique cases. Case
         endings are terminations by which certain cases are
         distinguished. In old English, as in Latin, nouns had
         several cases distinguished by case endings, but in
         modern English only that of the possessive case is
         retained.
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   Action on the case (Law), according to the old
      classification (now obsolete), was an action for redress
      of wrongs or injuries to person or property not specially
      provided against by law, in which the whole cause of
      complaint was set out in the writ; -- called also
      trespass on the case, or simply case.

   All a case, a matter of indifference. [Obs.] "It is all a
      case to me." --L'Estrange.

   Case at bar. See under Bar, n.

   Case divinity, casuistry.

   Case lawyer, one versed in the reports of cases rather than
      in the science of the law.

   Case stated or Case agreed on (Law), a statement in
      writing of facts agreed on and submitted to the court for
      a decision of the legal points arising on them.

   A hard case, an abandoned or incorrigible person. [Colloq.]


   In any case, whatever may be the state of affairs; anyhow.


   In case, or In case that, if; supposing that; in the
      event or contingency; if it should happen that. "In case
      we are surprised, keep by me." --W. Irving.

   In good case, in good condition, health, or state of body.


   To put a case, to suppose a hypothetical or illustrative
      case.

   Syn: Situation, condition, state; circumstances; plight;
        predicament; occurrence; contingency; accident; event;
        conjuncture; cause; action; suit.
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WordNet (r) 3.0 (2006):

in case
    adv 1: if there happens to be need; "in case of trouble call
           911"; "I have money, just in case" [syn: in case, just
           in case]