noun. The act or an instance of calling back from one location or situation to the previous one.

noun. A second or follow-up audition, especially as one of a set of such auditions for a role in a play.

noun. A return telephone or radio call.

noun. A recall of a recently sold product by the manufacturer to correct a defect.

noun. The return of a situation to a previous position or state.

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

noun. A product recall because of a defect or safety concern.

noun. A function pointer passed to another function that the latter can call for notification purposes.

noun. a follow-up audition (casting)

noun. a joke which references an earlier joke in the same routine

"Your callback will be used within the main form, so you must not include any tags or a form submit button. register_widget_control ($name, $callback [, $width [, $height]]);"

call back