The keyword term functions collectively as a proper noun phrase. The core grammatical element, or head of the phrase, is the simple noun `parade`. All preceding and subsequent words serve as modifiers that specify the unique identity of this particular event.
A detailed grammatical breakdown shows a hierarchy of modifiers. The head noun `parade` is specified by the compound noun `patriots day`, which functions as an attributive noun (a noun used as an adjective) to designate the occasion. This unit (`patriots day parade`) is then further specified by the proper nouns `boston` and `ma` (Massachusetts), which act as adjectival locators. Each component progressively narrows the definition from a general concept (a parade) to a singular, identifiable entity.
In this context, the part of speech crucial for the article's main point is noun. The entire phrase's purpose is to name a specific thing, which is the fundamental role of a noun. This allows the term to act as a clear and unambiguous subject, identifying the precise topic for discussion without requiring additional context.
