September 11th World Trade Center
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." ...