noun
September 11 attacks; 9/11
Refers specifically to the coordinated terrorist attacks in the United States on September 11, 2001. Used as a proper noun in news and historical contexts.
アメリカ同時多発テロから20年以上が経った。
More than 20 years have passed since the September 11 attacks.
Compound of アメリカ (America), 同時 (simultaneous), 多発 (multiple occurrences), and テロ (terrorism).