highjack vs highjacker

highjack and highjacker both are nouns.

Word	Noun	Adjective	Verb	Adverb
highjack	Yes	No	Yes	No
highjacker	Yes	No	No	No

highjack (noun)	highjacker (noun)
seizure of a vehicle in transit either to rob it or divert it to an alternate destination	a holdup man who stops a vehicle and steals from it
	someone who uses force to take over a vehicle (especially an airplane) in order to reach an alternative destination

highjack (verb)	highjacker (verb)
take arbitrarily or by force