9/11

/ˌnaɪn.əˈlɛ.vən/

9/11 proper noun: september 11, 2001; The date of the attacks on the World Trade Center and the Pentagon in the United States.

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Proper noun

9/11

September 11, 2001; The date of the attacks on the World Trade Center and the Pentagon in the United States.

Synonyms:

September eleventh
(metonymically) The attacks themselves.
- What is unbearable, in fact, is the feeling, 13 years after 9/11, that America has been chasing its tail; that, in some whack-a-mole horror show, the quashing of a jihadi enclave here only spurs the sprouting of another there; that the ideology of Al Qaeda is still reverberating through a blocked...2014 November 17, Roger Cohen, “The horror! The horror! The trauma of ISIS”, in The New York Times, New York, N.Y.: The New York Times Company, →ISSN, →OCLC, archived from the original on 10 Jun 2021
- Republican front-runner twisted his arms in apparent imitation of Serge Kovaleski’s arthrogryposis as he reiterated controversial 9/11 claims2015 November 26, Claire Phipps, “New York Times slams 'outrageous' Donald Trump for mocking reporter's disability”, in The Guardian, London: Guardian News & Media, →ISSN, →OCLC, archived from the...
Synonyms:

September eleventh

9/11 (plural 9/11s)

An event comparable to the September 11 attacks.
- Eleven million Spaniards responded to "their 9/11" by demonstrating in the rain against terrorism and their government's policies.2005, Peter H. Merkl, The Rift Between America And Old Europe: The Distracted Eagle, Routledge, page 73
- "I thought about ... the consequences for me saying I was a part of 9/11. I decided to just put my trust in God and tell the truth and time will tell," he said.2006 April 14, “Moussaoui says he wants more 9/11s”, in The Age, archived from the original on 24 Jan 2022
(Internet, humorous) A negative event that a person or a group of people have experienced whose impact is, hyperbolically, comparable to that of the September 11 attacks.
- This was my 9/11.
- 9/11 for unfunny people

But experts who have studied these other "9/11s" say some offer important revelations, by comparison, about how America responded to its own.2006, Michael Weissenstein, “Nations respond to their '9/11s'”, in International Institute for Strategic Studies, archived from the...
Drawing a US analogy, he said the weekend’s attack, for Israel, “could be a 9/11 and a Pearl Harbor wrapped into one”.2023 October 9, Ben Doherty, “Israel military says situation ‘dire’ in south as 260 bodies retrieved from festival”, in Katharine Viner...

From the date September 11 written numerically with the notation used in the United States, in the month–day format.

4 more rhymesFewer rhymes

What does 9/11 mean?: 9/11 means september 11, 2001; The date of the attacks on the World Trade Center and the Pentagon in the United States.
How do you use 9/11 in a sentence?: But experts who have studied these other "9/11s" say some offer important revelations, by comparison, about how America responded to its own.
What part of speech is 9/11?: 9/11 can be a proper noun or a noun.
How do you pronounce 9/11?: 9/11 is pronounced /ˌnaɪn.əˈlɛ.vən/.

Adapted from Wiktionary: 9/11 (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

Last updated: 2026-09-02

Pronunciation audio from Wikimedia Commons, each file under its own free license: en-us-nine eleven.ogg.

Cite this entry: “9/11.” Word.ws, https://word.ws/9%2F11. Based on Wiktionary, CC BY-SA 4.0.