Hijack vs Undefined - What's the difference?

As a verb hijack

is to forcibly stop and seize control of some vehicle in order to rob it or to reach a destination (especially an airplane, truck or a boat).

is an instance of hijacking; the illegal seizure of a vehicle.

lacking a definition or value.

(wikipedia hijack)

* hi-jack, highjack

(en verb)

To forcibly stop and seize control of some vehicle in order to rob it or to reach a destination (especially an airplane, truck or a boat).

To seize control of some process or resource to achieve a purpose other than its originally intended one.

(computing) To seize control of a networked computer by means of infecting it with a worm or other malware, thereby turning it into a zombie.

(computing) To change software settings without a user's knowledge so as to force that user to visit a certain web site (to hijack a browser ).

(politics) To introduce an amendment deleting the contents of a bill and inserting entirely new provisions.

* hijackable * carjack * seajack

(en noun)

An instance of hijacking; the illegal seizure of a vehicle.

An instance of a seizure and redirection of a process.

(politics) An amendment which deletes the contents of a bill and inserts entirely new provisions.

(poker slang) Preflop, the position two before the dealer.

(wikipedia undefined) (-)

Lacking a definition or value.

(mathematics, computing) That does not have a meaning and is thus not assigned an interpretation.

The result of division by zero is undefined .

* defined