The keyword term "11 Sep attack" functions as a noun phrase. The core or head word of this phrase is the noun "attack."
In this grammatical construction, "11 Sep" (an abbreviation for September 11) acts as an adjectival modifier. It specifies which particular attack is being referenced, functioning similarly to an adjective. This type of modifier, where a noun or a proper noun phrase modifies another noun, is known as an attributive noun or a noun adjunct. The modifier "11 Sep" narrows the scope of the general noun "attack" to a singular, specific historical event.
Identifying the term as a noun phrase is crucial because it determines its role within a sentence. As a cohesive unit, it can act as a subject, an object, or a complement, allowing it to be treated as a single entity in textual analysis, database indexing, and semantic searches. This classification ensures that the phrase is understood not as separate words but as a specific signifier for a well-defined event.
