The keyword phrase functions as a proper noun. It operates as a single grammatical unit to name a specific, unique historical event intrinsically linked to a particular location. Although composed of multiple words, including a date and the name of a building complex, the entire phrase is treated as one cohesive noun that identifies a singular entity in history and public consciousness.
Grammatically, the phrase is a compound noun. The core element, "World Trade Center," is itself a proper noun. The preceding date, "September 11th," acts as an adjectival modifier, specifying the particular context or event associated with that location. This formation creates a more specific, lexicalized noun phrase that has become a standalone term. It is treated as a single item in the mental lexicon, similar to other compound proper nouns like "the Eiffel Tower" or "the American Revolution."
Recognizing the term as a proper noun is essential for its correct use within an article. This classification dictates its function in a sentence, where it can serve as a subject, a direct object, or the object of a preposition. This understanding ensures grammatical precision when constructing sentences that refer to the event, its aftermath, or its memorialization, allowing for clear and coherent exposition.
