September 11, 2001, the day on which four airliners were hijacked by terrorists for use in an attack on the U.S.: two were flown into the towers of the World Trade Center in Manhattan, one into the Pentagon, and the fourth crashed into a Pa. field.
September 11, 2001, the date on which two hijacked airliners were flown into the World Trade Center in New York City and another into the Pentagon. A fourth hijacked airliner crashed in open land in Pennsylvania.
The attack itself.
An event comparable to 9/11.
Other Word Forms
Origin of 9
- From the date September 11 written in numbers according the format used in the United States, which puts the month before the day.