- The definition of hijack is to take over something that doesn't belong to you such as a plane, ship, bus or other vehicle, to commandeer or to take over by force.
- When you take control of a conversation others were having and make it all about you, this is an example of a time when you hijack the conversation.
- When the terrorists on 9/11 took over the plane and used it to crash into the World Trade Center in New York City, this is an example of the hijack of a plane by terrorists.
- to steal (goods in transit, a truck and its contents, etc.) by force
- to steal such goods from (a person) by force
- to cheat, swindle, etc. by or as by the use of force
- to seize control forcibly of (an aircraft, bus, ship, etc.), esp. in order to go to a nonscheduled destination
Origin of hijack; from hobo slang for robbing sleeping men ; from high + jack: origin obscure
transitive verbhi·jacked, hi·jack·ing, hi·jacks also high·jacked or high·jack·ing or high·jacks
- a. To seize control of (a vehicle such as an airplane or bus) by use of force, especially as a way of reaching an alternate destination or as an act of terrorism.b. To kidnap (a person in a vehicle): people who have experienced the trauma of being hijacked.c. To stop and rob (a vehicle in transit).d. To steal (goods) from a vehicle in transit.
- a. To take control of (something) without permission or authorization and use it for one's own purposes: dissidents who hijacked the town council; spammers who hijacked a computer network.b. To steal or appropriate for oneself: hijacked her story and used it in his own book.
Origin of hijackProbably back-formation from highjacker, perhaps from jacker, holdup man, from jack, to jacklight.
(third-person singular simple present hijacks, present participle hijacking, simple past and past participle hijacked)
- 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.
Blend of highway and jacker (“one who holds up”) 
hijack - Legal Definition