Source : Webster's Revised Unabridged Dictionary (1913)

Institution \In`sti*tu"tion\, n. [L. institutio: cf. F.
   institution.]
   1. The act or process of instituting; as:
      (a) Establishment; foundation; enactment; as, the
          institution of a school.

                The institution of God's law is described as
                being established by solemn injunction.
                                                  --Hooker.
      (b) Instruction; education. [Obs.] --Bentley.
      (c) (Eccl. Law) The act or ceremony of investing a
          clergyman with the spiritual part of a benefice, by
          which the care of souls is committed to his charge.
          --Blackstone.

   2. That which instituted or established; as:
      (a) Established order, method, or custom; enactment;
          ordinance; permanent form of law or polity.

                The nature of our people, Our city's
                institutions.                     --Shak.
      (b) An established or organized society or corporation; an
          establishment, especially of a public character, or
          affecting a community; a foundation; as, a literary
          institution; a charitable institution; also, a
          building or the buildings occupied or used by such
          organization; as, the Smithsonian Institution.
      (c) Anything forming a characteristic and persistent
          feature in social or national life or habits.

                We ordered a lunch (the most delightful of
                English institutions, next to dinner) to be
                ready against our return.         --Hawthorne.

   3. That which institutes or instructs; a textbook; a system
      of elements or rules; an institute. [Obs.]

            There is another manuscript, of above three hundred
            years old, . . . being an institution of physic.
                                                  --Evelyn.

Source : WordNet®

institution
     n 1: an organization founded and united for a specific purpose
          [syn: {establishment}]
     2: an establishment consisting of a building or complex of
        buildings where an organization for the promotion of some
        cause is situated
     3: a custom that for a long time has been an important feature
        of some group or society; "the institution of marriage";
        "the institution of slavery"; "he had become an
        institution in the theater"
     4: the act of starting something for the first time;
        introducing something new; "she looked forward to her
        initiation as an adult"; "the foundation of a new
        scientific society"; "he regards the fork as a modern
        introduction" [syn: {initiation}, {founding}, {foundation},
         {origination}, {creation}, {innovation}, {introduction},
        {instauration}]
     5: a hospital for mentally incompetent or unbalanced person
        [syn: {mental hospital}, {psychiatric hospital}, {mental
        institution}, {mental home}, {insane asylum}, {asylum}]