Anaphor

An anaphor is an element which depends for its reference on the reference of another element.

In binding theory, anaphor is an element which must be A-bound by an antecedent within its binding domain.

Examples
Himself in (a) is an anaphor with John as its antecedent. The ill-formedness of (b) and c is due to the lack of a proper antecedent: himself does not agree in person features with I in (b), and John is outside the binding domain in (c).

(a)	John hates himself. (b) *I hate himself. (c) *John says that I hate himself.

Comment
Traces of NP-movement are also considered as anaphors.

Link
Utrecht Lexicon of Linguistics