universal property

Short definition from Wiktionary

Noun

1. 1
   The property of there being a unique morphism from an arbitrary object to the universal morphism of a comma category which is from a functor to a fixed object; or, dually, the property of there being a unique morphism from the universal morphism to an arbitrary object of a comma category which is from a fixed object to a functor. (Caveat: the uniqueness is up to isomorphism.)