The keyword phrase "patriots day holiday in ma" functions as a noun phrase. The main point or head word within this phrase is the noun "holiday".
Grammatically, the phrase is constructed with multiple modifiers clarifying the head noun. "Patriots Day" is a proper noun acting as a noun adjunct, which functions like an adjective to specify which particular "holiday" is being discussed. The subsequent prepositional phrase, "in ma," acts as an adjectival phrase, further modifying the noun "holiday" by specifying its geographic location (Massachusetts).
Therefore, for the purpose of creating an article, the central concept is the "holiday" itself. The terms "Patriots Day" and "in ma" serve to define and narrow the scope of this core subject, establishing it as a specific, named event within a particular place. The entire phrase should be treated as a single conceptual unit representing a specific entity.
