Grammatically, the term functions as a noun phrase. "9/11" serves as a proper adjective modifying the noun "hijackers," specifying the individuals who carried out the attacks on September 11, 2001. This phrase refers to the 19 men affiliated with the extremist group al-Qaeda who commandeered four commercial airliners in a coordinated act of terrorism against the United States.
The 19 individuals operated in four teams, one for each hijacked aircraft. American Airlines Flight 11 and United Airlines Flight 175 were crashed into the North and South Towers of the World Trade Center in New York City, respectively. American Airlines Flight 77 was crashed into the Pentagon in Arlington, Virginia. The fourth plane, United Airlines Flight 93, crashed into a field in Shanksville, Pennsylvania, after passengers and crew attempted to regain control from the assailants. The intended target of Flight 93 is believed to have been a prominent landmark in Washington, D.C., such as the U.S. Capitol or the White House.
The analysis of this group's organization, motivations, and methods has been a central focus of counter-terrorism studies and intelligence efforts since the event. Their actions directly precipitated major shifts in global security protocols, particularly in aviation, and led to long-term military and political responses, including the U.S.-led War on Terror. The term's usage is therefore critical in historical, political, and security contexts to precisely identify the perpetrators of these specific attacks.
