What is the meaning of Callback?

The return of a situation to a previous position or state; a reference to such a position or state.

A return telephone or radio call; especially one made automatically to authenticate a logon to a computer network.

A product recall because of a defect or safety concern.

A function pointer passed as an argument to another function.

A follow-up audition in casting.

A follow-up interview in employment recruiting.

A joke which references an earlier joke in the same routine.

A form of audience participation in which the audience shout lines in response to the dialog of a film.

Source: wiktionary.org