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

It was particularly hard-hit on 9/11, with the surrounding Nassau County losing around 350 people, including many first responders.

From BBC • Apr. 10, 2026

Founded in the wake of the 9/11 attacks and funded by the CIA’s venture-capital arm, Palantir sought to target terrorists and defend American interests.

From MarketWatch • Apr. 4, 2026

Shortly after the 9/11 terrorist attacks, Fulop quit his job as a Goldman Sachs trader to join the Marines and deploy to Iraq.

From The Wall Street Journal • Mar. 25, 2026

Six days after 9/11, George W. Bush visited the Islamic Center of Washington and declared “Islam is peace.”

From Salon • Mar. 12, 2026

How many times did he re-up after 9/11?

From "All American Boys" by Jason Reynolds