The phrase is grammatically classified as a noun phrase. Its primary function is to act as a single noun within a sentence, capable of serving as a subject, object, or complement. The core of the phrase is the head noun, which is modified by a subsequent prepositional phrase that specifies its temporal scope.
A detailed analysis of its components reveals a clear grammatical structure. The word "months" serves as the head noun, establishing the subject as a unit of time. The segment "until september 11 2025" is a prepositional phrase that functions as an adjectival post-modifier, describing and limiting the head noun. Within this modifying phrase, "until" is the preposition, indicating a terminal point in time. The object of the preposition is "september 11 2025," a proper noun phrase that specifies the exact date serving as that terminal point.
In practical application, this structure allows a concept of duration to be treated as a quantifiable entity. The phrase answers the implicit question "what?" or "how many?" in a temporal context. For example, it can act as the subject in "The number of [months until september 11 2025] is X" or as the direct object in "The project plan calculates the [months until september 11 2025]." Its construction transforms a temporal query into a discrete grammatical unit that can be integrated into a wide variety of syntactic constructions.
