Could one use the definite article with 9/11?

This is an example sentence composed by me:

The author traces the origins of modern terrorism back to the late 19th century, but he admits that (the) 9/11 was an important event in this long history.

It seems that 9/11 works like a proper noun, but I find some examples of it being used with the, although they seem to have been penned by non-native speakers of English:

In this regard, global media reporting on the 9/11 was as much a battling field for the definition of shared values of democracy around the globe as it was a spectacular stage for the local political and public elites to portion the field for ... (Tomasc Pludowski)

Will "the 9/11" sound strange to native speakers of English, or will it look like a minor error or just like a variation, an author's choice of article?

Could one view the 9/11 as an elliptical variant of "the 9/11 attacks"?

  • 7
    Yes "the 9/11" is weird.
    – MaxW
    Commented Feb 13, 2016 at 5:50
  • english.stackexchange.com/questions/59271/…
    – dinerdash
    Commented Feb 13, 2016 at 6:06
  • @dinerdash - thank you, but there's no discussion of the use of the definite article with events. The Empire State Building is quite different from a series of terrorist attacks. Commented Feb 13, 2016 at 6:31
  • 3
    Consider Christmas - you wouldn't say "The Christmas is an important holiday." You might say "The Christmas holiday is important." Any place I see "the 9/11" I think that attacks has been omitted "The 9/11 attacks were an important event." "9/11 is a date that will live in infamy."
    – ColleenV
    Commented Feb 16, 2016 at 1:52

5 Answers 5


We do not use an article before "9/11". Americans would think the use of "the" in the sentence you quote as decidedly strange-sounding.

9/11 is a date.

We do not use an article before a date when it is expressed as month - day - year or simply month - day. "I was born on December 5, 1958." NOT "I was born on the December 5, 1958."

Occasionally people give the day first and then the month, or just the day. In that case, we DO give an article before the day. "I was born on the fifth of December", or "I was born on the fifth".

We do not normally use an article before a day of the week. "I met Sally on Wednesday". "Our club meets on Wednesdays." We DO use an article when giving a "formula" to describe which a date by the day of the week, like, "Memorial Day is the fourth Monday in May."

The fact that 9/11 is a date associated with a specific event, and is sometimes used as a sort of name for that event, doesn't change the rules. The same is true for other historically significant days. We say, "The Declaration of Independence was signed on July 4, 1776", NOT "... on the July 4". Or, "We remember December 7 as Pearl Harbor Day", NOT "the December 7", etc.

If you use a date as an adjective, then whether it calls for an article depends on the noun, and the date is irrelevant. Usually there would be an article. "Sally served on the 9/11 Commission", "We built a 9/11 memorial", etc. The only example I can think of where you wouldn't have an article is if it was a title, like "Fred was elected 9/11 Memorial Co-ordinator".


You would not use an article with a date, any more than you would write:

He admits that the Wednesday was an important date in history.

However you could write:

...but he admits that the 9/11 attack was an important event in this long history.

as the noun is now attack.

  • 1
    I disagree with this answer, simply because "the fourth of July" is common enough. In fact, using an article with a date is frequently found in conversation. "I'll see you on the 16th." "I was born in the 80's." "It was the Monday after Thanksgiving." And 9/11 is not simply a date, it is also an event. It's more akin to Pearl Harbor, which does not simply refer to a place.
    – dinerdash
    Commented Feb 14, 2016 at 0:01
  • @dinerdash No, "9/11" by itself is only a date, without adding "9/11 (what)". There is one every year. Are you saying "the Dec. 7" is OK?
    – user3169
    Commented Feb 14, 2016 at 0:38
  • 3
    The original question says, "9/11 was an important event". In context it is clearly not just a date. There is a ninth of September every year, but there is not a 9/11 every year in the sense that the question considers. To be clear, I don't think "the 9/11" is correct. I just think "you would not use an article with a date" is wrong. It may be true in this instance but it is not a real answer.
    – dinerdash
    Commented Feb 14, 2016 at 20:45
  • I'll keep an eye out for a better answer. I was trying to focus on the example, but if there is a better explanation I'll yield to it.
    – user3169
    Commented Feb 14, 2016 at 21:01

The 9/11 is not idiomatic as we don't use the definite article for historical events unless it starts with the ordinal number or it has modifiers (an adjective, a noun adjunct or a prepositional phrase). Historical Events are very close to people's names for which we don't use the definite article. Also everybody (who knows about the event) can identify such an event without the help of the definite article.

If you contrast World War One, World War Two with the First World War, the Second World War, it becomes clear. The War of the Roses has the definite article because it is modified by of the Roses and the Great War (a.k.a. World War One), the Iraq War, the Afghanistan War (the War in Afghanistan) also use the the because they have the adjective great, the noun adjuncts Iraq, Afghanistan as a modifier. The Great Depression and The Great Recession are other examples.

Of course, when 9/11 modifies another noun as a noun adjunct, the definite article is necessary, e.g, the 9/11 Commission and the 9/11 Attacks.

Another example of a historical event expressed using a month and a date is Fourth of July and July Fourth, both of which don't require a definite article. However, if your birthday is 4th of July, you would write, "I was born on the 4th of July". It clearly shows the difference between using a definite article for a non-historical event (your birthday) and not using it for a historical event (Independence Day).

We don't use the definite article for Independence Day even though the noun Day is modified by the noun adjunct Independence. The same rule applies to Memorial Day and Martin Luther King Jr. Day, etc. They are all proper nouns at least in the United States.

However, if you talk about Independence Day of other countries, you have to use the definite article, e.g., "the Korean Independence Day", "the Singapore Independence Day".

Whoever wrote the 9/11 was not aware of this grammatical rule.

  • 2
    But " I have a vacation day on the Fourth of July." It refers to the holiday, but you can't leave out the.
    – user3169
    Commented Feb 16, 2016 at 0:46
  • Not sure why this answer was voted down, while there are exception cases this goes a very long way towards answering the question
    – PerryW
    Commented Feb 16, 2016 at 1:00

The conundrum with 9/11 is that it is composed of numbers (digits) and is also a name and represents a significant historical event and a calendar date

9/11 is usually read as the two numbers nine-eleven and should not be confused with nine-one-one which is the emergency number to dial in the US. The events of that day are sometimes referred to as The Events of September 11th.

Articles are not (usually) used when speaking about numbers

1, 2, 3, 4, 5, ...

Dial 999 (nine-nine-nine) for emergency services in the UK
Call 911 (nine-one-one) for the police in the US

Possible exceptions are

I'm going to the 7-11 (seven-eleven is a location, a convenience store)

Let me give you the 411 (four-one-one) on him
411 was the number for telephone information services in the US and was used as shorthand for information for a time

Articles can be used with cardinal numbers as they can be used as adjectives

one, two, three, four, five...

The Seven Samurai
Just the two of us.
Is it only you? Just the one?

Articles can be used with ordinal numbers as they can be used to describe ordering or distribution

first, second, third, fourth, fifth...

The Fourth of July
The Fifth of November

Articles are not used when referencing historical events by name

Pearl Harbor
Bloody Sunday

Articles are not used when referencing a named date

New Year's Day
Boxing Day
Memorial Day
Labor Day
Martin Luther King Day
Chinese New Year

Similar to Christmas, Easter, or Chinese New Year, 9/11 refers not only to the events of the day but also the days either before and or after it

9/11 is a uniquely named event

If there were to be more than one 9/11 then an article (or something) might be necessary to differentiate the two.

Let's hope an article will never be necessary.


Could one use the definite article with 9/11?


But not in your sentence.

The author traces the origins of modern terrorism back to the late 19th century, but he admits that (the) 9/11 was an important event in this long history.

It would not be correct to use the definite article here, because 9/11 is being used as a proper noun. This is shown by your use of event and not date. It seems Tomasc Pludowski is also referring to the event, and so he is also incorrect in his usage of the before 9/11.

You ask other questions:

Will "the 9/11" sound strange to native speakers of English, or will it look like a minor error or just like a variation, an author's choice of article?

In both your sentence and Pludowski's the 9/11 both sounds strange and will be taken as an obvious grammatical error. Whether a native speaker would classify it "minor" or not depends on how you define "minor". It is not one that reputable publishers in the US or the UK would allow to go uncorrected. It sounds glaringly wrong. It is not a variation or stylistic choice.

Could one view the 9/11 as an elliptical variant of "the 9/11 attacks"?

No. Not even when you have referred to the 9/11 attacks previously in the same text. This is because many more things besides "attacks* were part of the event. You could use such phrases as the ones on 9/11 or those of 9/11 to refer to the 9/11 attacks.

For 9/11 (and its variants such as Nine-Eleven and 9-11) as a proper noun or name, see the following:

  1. American Dialect Society's Word of the Year for 2001 (link)

9-11 Terrorist attacks of Sept. 11, 2001

  1. Global Language Monitor (link)

The first case is the use of 9/11, itself, as a shorthand for the 2001 terrorist attacks. Using various web metrics, 9/11 outpaces any other name, including the spelled out ‘September 11th” by 7:1 margin.

  1. MacMillan Dictionary BuzzWord (link)

September 11th 2001, the day when planes flown by terrorists destroyed the World Trade Center in New York and damaged the Pentagon, killing thousands of people

Read the entire piece, as the blog makes it clear that 9/11 is used as a word and not only as a date.

  1. alpha Dictionary (link)

Meaning: The terrorist attack on the World Trade Center in New York in which 2,993 people from 90 nations perished on September 11, 2001. Terrorists also struck the Pentagon in Washington but failed to reach one other unknown target on the same day.

You could use the definite article with 9/11 in the same situations that you can use it with other proper nouns and names. This is to specify further.

'You had lunch with Beyoncé, you mean the Beyoncé?!'

similar use:

'I'm confused. Are you sure you're talking about the 9/11 and not any old 9/11, because I remember things differently regarding it.'

We can also use the when talking about different manifestations or experiences of it:

The 9/11 you went through was much more personal than the 9/11 reported on by most newspapers.

9/11, much like Pearl Harbor, is also used as a common noun, and in fact a verb ('I am going to 9/11 your ass all over the place'); see Urban Dictionary for other examples.

The two events are related, of course, as attacks upon US soil that killed in the thousands. A Pearl Harbor is now

a(ny) surprise attack often with devastating effect

See Merriam-Webster online dictionary, where this is the first definition, before that of the place name.

There is another definition for Pearl Harbor that applies equally to 9/11 as a common noun, found in International Dictionary:

A seminal dramatic event that unites a community and arouses it into action against an enemy

This is for Pearl Harbor, which has now been converted to a common noun, that is, one that refers to a class of events. But as per Urban Dictionary and the main stream press, we also use 9/11 in this way, such as

"Such-and-such country has not experienced its own 9/11."

The proper noun 7/7 refers to the terrorist bomb attacks of July 7, 2005 in London.

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