Coreference

Coreference

In generative syntax, if two referential elements (NPs) in a structure refer to the same entity, i.e. have the same reference, this is called coreference.

Example
In John says that he has been here before, the NPs John and he can be co-referential. Coreference is usually indicated by coindexing: Johni says that hei has been here before.

Link
Utrecht Lexicon of Linguistics