Definition of hijacker | Bee Dictionary of English

n a holdup man who stops a vehicle and steals from it
n someone who uses force to take over a vehicle (especially an airplane) in order to reach an alternative destination

On June 29, 2000, using the alias Isam Mansur, Aziz wired $5000 via Western Union from the United Arab Emirates to hijacker Marwan al-Shehhi in New York City.
Bin Laden "reportedly selected" Bin 'Attash, who lost a leg in a 1997 battlefield accident in Afghanistan, to be a 911 hijacker.
The hijacker also asked that women reporters and Calderon be at the airport to talk to him, Rios said.

FBI director, congressional leaders defend data mining
A top-secret program that collects phone records of Americans is legal, conducted properly and possibly could have helped detect a 9/11 hijacker had it been in place before the 2001 terrorist attacks, FBI Director Robert Mueller said Thursday.
June 14, 2013 - CNN
Revenge for fish guts prank motive in hijacking hoax
A Hawaii man is pleading guilty to making a hoax call to the FBI when he falsely reported a possible hijacker was aboard an Alaska Airlines flight to get revenge on a man he said put fish guts in his truck. Prosecutors said Timothy David Hershman of Kona admitted calling the FBI on Jan. 17 and saying another man was going to hijack a plane headed to Alaska. Authorities determined the other man ...
June 14, 2013 - KIRO 7 Seattle-Tacoma
Hawaii man pleads guilty to hijack threats
HONOLULU -- A Hawaii man is pleading guilty to making a hoax call to the FBI when he falsely reported a possible hijacker was aboard an airplane. Prosecutors say Timothy David Hershman of Kona admitted calling the FBI on Jan. 17 and saying another man was going to hijack a plane headed to Alaska. Authorities determined the other man was aboard an Alaska Airlines flight from Kona to Seattle. Two ...
June 14, 2013 - KGW NewsChannel 8 Portland

Zacarias Moussaoui in FOXNews
Asked by his lawyer why he signed his guilty plea in April as "the 20th hijacker," Moussaoui replied: "Because everybody used to refer to me as the 20th hijacker and it was a bit of fun."
Jafar as-Sadiq in The Canberra Times
Mr Sadiq said, "It is not clear whether there is one or more [hijacker], or whether they belong to Abdel Wahid."
Temel Kotil in Reuters
The hijacker gave a note to the head steward saying he had a bomb. After that the captain and crew acted in accordance with civil aviation procedure,Kotil told Reuters.