noun
September 11 attacks; 9/11
Refers specifically to the terrorist attacks on the United States on September 11, 2001. Used in news and historical contexts.
９１１事件はアメリカの歴史を大きく変えた。
The September 11 attacks greatly changed American history.
彼は９１１事件についてのドキュメンタリーを見た。
He watched a documentary about the 9/11 attacks.
A broader term for simultaneous terrorist attacks; often used in Japanese media to describe the 9/11 attacks, but can refer to any coordinated terrorist incident.
Compound of ９１１ (kyū-ichi-ichi, from the date September 11) and 事件 (jiken, 'incident'). A direct borrowing of the English '9/11' into Japanese date notation.