The keyword term functions as a proper noun phrase. It operates as a single grammatical unit to name a specific, unique historical event, conceptually binding the date and the location. As a noun, it can serve as the subject or object within a sentence, referring to the event as a singular entity.
This compound phrase is constructed from a temporal element ("September 11th") and a geographical locator ("New York City"), both of which are themselves proper nouns or contain them. While its primary function is nominal, the entire phrase can also be used adjectivally as a noun adjunct (or attributive noun). In this capacity, it modifies a subsequent noun, as seen in constructions like "the [...] memorial" or "[...] media coverage," where it describes the nature of the noun that follows.
Identifying this grammatical role is critical for precise and effective article construction. Recognizing the term as a noun allows it to be correctly positioned as the focal point of a sentence (e.g., "...remains a significant date in U.S. history"). Understanding its function as an adjective enables more concise and impactful phrasing, allowing a writer to avoid cumbersome prepositional phrases (e.g., using "the [...] response" instead of "the response to the events of..."). This syntactic control is essential for maintaining a clear, authoritative, and professional tone.
