The keyword term functions as a proper noun. It is the specific name of a public holiday ("Patriots' Day") as it is observed in a particular location, the U.S. state of Massachusetts ("MA"). As a single unit, it names a distinct cultural and civic event.
Grammatically, the phrase is a compound noun. The core element, "Patriots' Day," is the primary proper noun. The component "MA," the standard abbreviation for Massachusetts, acts as a noun adjunct (or noun modifier). In this role, it functions adjectivally to specify which version of the holiday is being referenced, distinguishing it from observances in other states like Maine or Wisconsin. This structure is common in English, as seen in phrases like "Boston Marathon" or "California coast," where one noun modifies another to create a more specific name.
Recognizing the term as a proper noun is critical for its application in writing. It dictates that the phrase should be capitalized consistently and treated as a single, indivisible concept representing the event. This ensures semantic precision, signaling to the reader that the article is about a specific, named occasion rather than a generic description. For content strategy and search engine optimization, treating the entire phrase as a singular entity aligns with user search intent for this specific event.
