1. an established practice, tradition, behavior, or system of roles and relationships, such as marriage, that is considered a normative structure or arrangement within a society. Sociologists usually distinguish between four main types of institutions: political (e.g., monarchy), economic (e.g., capitalism), cultural (e.g., media, education, religion), and social (e.g., family organization, race, gender).

2. a large, often publicly funded organization, such as a university, museum, or charitable foundation, or the building that houses such an organization.

3. a building or building complex in which individuals are cared for or confined for extended periods of time, especially a psychiatric hospital or a prison. —institutional adj.