The keyword phrase "911 lone star season 4" functions grammatically as a proper noun. It operates as a single, multi-word unit that names a specific, unique entity: the fourth season of the television series titled 911: Lone Star.
A proper noun is a name used for an individual person, place, or organization, spelled with an initial capital letter. In this case, "911: Lone Star" is the title of the show, which is the core proper noun. The addition of "Season 4" acts as a specific designator or modifier, narrowing the reference to a particular installment of the series. The entire phrase, however, is treated as a single nominal unit. It is analogous to other multi-word proper nouns like "The United States of America" or "World War II," where the component words combine to form one specific name.
For the purpose of constructing an article, recognizing this phrase as a proper noun is critical. It will function as the subject or object within a sentence. For example, in the sentence, "911 Lone Star Season 4 premiered in January 2023," the entire phrase serves as the subject. This grammatical classification dictates how it should be used in sentence structure and ensures clarity in referencing the specific television season.