The keyword phrase functions as a noun phrase. In this construction, the final word, "year," serves as the head noun, which is the core component that establishes the phrase's grammatical identity. The preceding words, "september 11th attack," act collectively as a modifier that specifies which particular year is the subject of discussion.
A detailed grammatical analysis reveals that "year" is the simple subject or head of the phrase. The unit "september 11th attack" operates as a compound adjectival modifier. Within this modifier, "attack" is a noun acting as an adjective (a noun adjunct) that modifies "year." Subsequently, the proper noun "September 11th," representing a specific date, functions as an adjective modifying "attack." This layering of modifiers creates a highly specific term that refers to a single, identifiable concept.
Recognizing the term as a noun phrase is essential for its correct application in writing. It can be used as the subject of a sentence (e.g., "The ... year marked a turning point."), the object of a verb, or the object of a preposition. This classification allows the entire multi-word term to be treated as a single conceptual unit, ensuring grammatical precision and enabling the construction of clear, coherent sentences around it.
