months-long

The compound adjective "months-long" is a modern English formation following a productive pattern for describing duration, akin to "hours-long" or "days-long." Its first element, "months," originates from the Proto-Germanic mēnōth-, which is related to "moon," reflecting the ancient method of timekeeping by lunar cycles. The second element, "long," derives from the Proto-Germanic langaz, meaning "long" in both spatial and temporal senses. The compound's logic is transparently literal, directly combining the plural form of the time unit with the adjective for extended duration to create a single descriptive term for an event spanning multiple months.

Structure: months (time period) + long (duration) - months: From Old English monað, meaning "month." In this compound, it functions as a noun specifying the unit of time. - long: From Old English lang, meaning "having great linear extent or duration." In this compound, it functions as an adjective indicating the extended nature of the specified time.