The keyword phrase functions as a proper noun phrase. It designates a specific, unique entity: a particular holiday ("Patriots Day") tied to a precise date ("April 21"). The core of the phrase is the noun "Day," which is modified and made specific by the other components.
Grammatically, "Patriots" acts as an attributive noun, modifying "Day" to name the holiday. The date, "April 21," functions as an appositive, a noun phrase that sits next to another noun to rename or describe it in another way. Together, they form a single conceptual unit that can act as the subject, object, or object of a preposition within a sentence. This structure distinguishes it from a verb, which denotes action, or an adjective, which describes a quality.
Identifying the term as a proper noun phrase is crucial because it establishes the article's main point as a specific event or entity. Consequently, the content should focus on defining, describing, or explaining this event. The article's narrative would revolve around this noun as its central subject, detailing its history, significance, or associated activities, rather than treating it as a descriptive quality or an action.
