Institution (noun)

1. A large and established organization, especially one devoted to education, charity, or healthcare.
2. An established custom, practice, or convention that has become part of the way society functions.

Origin:

Late middle english (in the sense "establishing, settling"): from latin institutio(n-), from instituere "set up".

Examples:

1. Harvarding has been an important institution in this area for centuries.
2. He was an active member of several civic institutions.
3. The hospital is one of the leading institutions in the field of medical research.
4. This institution is devoted to the care and rehabilitation of endangered species.
5. The institution of marriage has changed greatly over the past 50 years.