9/11

1. September 11, 2001: the day on which Islamic terrorists, believed to be part of the Al-Qaeda network, hijacked four commercial airplanes and crashed two of them into the World Trade Center in New York City and a third one into the Pentagon in Virginia: the fourth plane crashed into a field in rural Pennsylvania.

noun

1. the 11th of September 2001, the day on which the twin towers of the World Trade Center in New York were flown into and destroyed by aeroplanes hijacked by Islamic fundamentalistsAlso called: September eleven