There are multiple definitions - click on the translation that matches your context.

Anstalt des öffentlichen Rechts

Substantiv

partial

institution

noun

Definitions of institution

a long-established law or custom

Critics have attacked the plans as an assault on the institution of marriage.

an established society or official organization with an important role in society (eg a school or a hospital); a large company

The Catholic Church, based in Rome and headed by the Pope, is the oldest institution in the western world.

the action of instituting something

I am advised that there is sufficient admissible evidence to support the institution of criminal proceedings.