The keyword phrase functions grammatically as a proper noun. It serves as the specific title of a song by the artist Tyler, the Creator. This title combines two distinct but thematically connected parts of a single track, "911" and "Mr. Lonely," from the 2017 album Flower Boy. As a complete unit, its grammatical purpose is to name this unique artistic work.
This classification is based on the phrase's function rather than the individual parts of speech of its components. While "911" is a numeral, "Mr." is a title, and "lonely" is an adjective, their combination in this context creates a singular, unique identifier. The construction "Mr. Lonely" personifies an emotional state, effectively treating it as a named entity. The complete expression does not modify another noun or describe an action; it stands alone as the official name of the song, which is the defining characteristic of a proper noun.
For the purpose of analysis or writing, treating the phrase as a singular proper noun is crucial for correct syntax and interpretation. It should be handled as a single grammatical unit, similar to a person's name or the title of a book. The common stylization of the track as "911 / Mr. Lonely" further reinforces its status as a compound title that functions as one cohesive proper noun.
