The term "September 11 attacks" functions as a proper noun phrase. In this construction, the head noun is "attacks," which is being modified by the preceding words. This phrase refers specifically to the series of four coordinated terrorist attacks by the Islamic terrorist group al-Qaeda against the United States on the morning of Tuesday, September 11, 2001.
Grammatically, the phrase is composed of the noun "attacks," which is specified by the proper noun "September 11" acting as an adjectival modifier. "September 11" is used attributively to specify the date on which the events occurred, distinguishing them from any other attacks. This structure is common in English for naming specific historical events, where a date, place, or key figure modifies a general noun (e.g., the "Normandy landings," the "Kennedy assassination").
The use of this term as a proper noun phrase is significant because it consolidates a complex set of eventsincluding two plane crashes into the World Trade Center, one into the Pentagon, and one in a field in Pennsylvaniainto a single, identifiable historical concept. This linguistic convention allows for concise and unambiguous reference in historical, political, and cultural discourse, cementing the event as a singular, defining moment in contemporary history.
