The compound adjective "weeks-long" is a modern English formation following a productive pattern for indicating duration. The first element, "weeks," derives from the Old English concept of a "turning" or cycle, which evolved to signify a standard seven-day period. The second element, "long," originates from the Proto-Germanic term for extended linear space, which was metaphorically applied to temporal extension. The combination literally means "having the length of weeks," where the plural noun in the genitive construction ("weeks") specifies the measure, and "long" provides the qualitative sense of extent, resulting in the abstract meaning of an event or state persisting through that multiple-week timeframe.

Structure: weeks (plural noun) + long (adjective) - weeks: From Old English wice, wicu ("a turning, succession, change"), of Germanic origin. Functions as a plural noun indicating a measure of time. - long: From Old English lang, long ("having considerable linear extent, lasting"), of Germanic origin. Functions as an adjective describing duration.