The keyword term "11 sep festival" functions grammatically as a noun phrase. The core part of speech, which serves as the main point of the term, is the noun "festival."
In this construction, "festival" is the head noun that identifies the subject as a type of event or celebration. The preceding component, "11 sep," is a proper noun (representing the date September 11th) that functions as a noun adjunct. A noun adjunct is a noun used to modify another noun. In this role, "11 sep" acts adjectivally, specifying and distinguishing this particular festival from any other.
Identifying the term as a noun phrase is essential because it dictates its grammatical role within a sentence. It can function as a subject (e.g., "The 11 sep festival begins at noon."), a direct object (e.g., "We are planning the 11 sep festival."), or the object of a preposition. This classification establishes the term as a distinct entity, which is the central topic of the article.