The keyword phrase "patriots day massachusetts boston marathon" functions grammatically as a compound noun. It is a string of proper nouns that collectively name a single, specific event. In this construction, the final word, "marathon," serves as the head noun, while the preceding words"Patriots Day," "Massachusetts," and "Boston"act as noun adjuncts or attributive nouns, modifying the head noun to create a highly specific identifier.
The grammatical structure is built through a process of sequential modification. "Boston" modifies "Marathon" to specify which marathon. "Massachusetts" further modifies "Boston Marathon" to specify the state-level location. Finally, "Patriots Day" modifies the entire subsequent phrase, specifying the occasion on which the event occurs. This stacking of nouns, where each noun functions adjectivally to the one(s) following it, is a common feature in English for creating precise terminology. The entire phrase operates as a single syntactic unit, similar to a single-word proper noun.
For practical application in an article, this phrase must be treated as a single noun entity. It can serve as the subject of a sentence (e.g., "[The phrase] is a celebrated annual race."), the direct object (e.g., "The city hosts [the phrase]."), or the object of a preposition (e.g., "She wrote about [the phrase]."). Recognizing its function as a compound noun is critical for maintaining correct sentence structure and ensuring the phrase is indexed cohesively as a single topic by search engines and readers.
