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• 9/11
  9/11

  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.
• 9-11
  9-11

  See September 11 attacks.

9/11

American  

[nahyn-i-lev-uhn] / ˈnaɪn ɪˈlɛv ən /

Or 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.

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9-11 Cultural  

1. See September 11 attacks.

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Etymology

Origin of 9/11

First recorded in 2000–05

Example Sentences

See Examples For:

9/11 9-11

“Everything I thought I wanted to say about war in ‘Devil’s Backbone’ seemed obsolete, because we had gone through 9/11 and the world had changed,” Del Toro recalls.

From Los Angeles Times ● Oct. 9, 2026

In 2000, the year before 9/11, Windows on the World—the glamorous dining establishment in the North Tower of the World Trade Center—was the highest-grossing restaurant in the U.S.

From The Wall Street Journal ● Sep. 18, 2026

To secretly persuade his young students to put on a musical about the horrors of 9/11 and its aftermath that’s certain to cause controversy and get the principal in trouble.

From Los Angeles Times ● Sep. 18, 2026

A football club has apologised after it published images of a new clothing line with "United 93" printed on the back - the call sign of one of the aircraft hijacked on 9/11.

From BBC ● Sep. 18, 2026

Prior to 9/11, terrorists were prosecuted in civilian courts.

From Nazi Saboteurs by Samantha Seiple

Unions called the February 9-11 strike, accusing the authorities of ignoring warnings about the safety of infrastructure and failing to invest enough in the network.

From Barron's ● Feb. 9, 2026

Sam, in year six, says he thinks we should have longer holidays "because, in countries like Ireland and Spain, they have 9-11 weeks."

From BBC ● Jul. 19, 2025

The Valley Leadership Academy in Bacup will roll out the remote lessons from September for top set students in years 9-11.

From BBC ● Jul. 16, 2025

It also dropped them to 3-6 in their last nine games and 9-11 in their last 20.

From Los Angeles Times ● May 25, 2025

Tull, Jethro, theory of, on plant-growth, 9-11, 69, 109.

From Manures and the principles of manuring by Charles Morton Aikman