Dictionary.com Unabridged (v 1.1) - Cite This Source - Share This

American Heritage Dictionary - Cite This Source - Share This

in·sti·tu·tion       (ĭn'stĭ-tōō'shən, -tyōō'-)  Pronunciation Key  n.   The act of instituting. A custom, practice, relationship, or behavioral pattern of importance in the life of a community or society: the institutions of marriage and the family. Informal One long associated with a specified place, position, or function. An established organization or foundation, especially one dedicated to education, public service, or culture. The building or buildings housing such an organization. A place for the care of persons who are destitute, disabled, or mentally ill. An established organization or foundation, especially one dedicated to education, public service, or culture. The building or buildings housing such an organization. A place for the care of persons who are destitute, disabled, or mentally ill.

Online Etymology Dictionary - Cite This Source - Share This
institution 

WordNet - Cite This Source - Share This

institution
noun
1.	an organization founded and united for a specific purpose
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" [syn: initiation]
5.	a hospital for mentally incompetent or unbalanced person [syn: mental hospital]

Merriam-Webster's Dictionary of Law - Cite This Source - Share This
Main Entry: in·sti·tu·tion
Function: noun
1 : the act of instituting
2 : a significant practice, relationship, or organization in a society or culture institution of marriage>
3 : an established organization or corporation esp. of a public character; specifically : a facility for the treatment or training of persons with mental deficiencies

Webster's Revised Unabridged Dictionary - Cite This Source - Share This

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.