hours-long

The compound adjective "hours-long" is a modern English formation following a productive pattern for indicating duration. The first element, "hours," traces back through Old English to the Latin hōra, which itself was borrowed from Greek hōra, originally meaning a limited period of time or season. The second element, "long," is a native Germanic word from Old English, with a stable core meaning of extended temporal or spatial length. The compound logically combines these elements to denote an event or state whose length is measured on the scale of hours, a straightforward descriptive construction that emerged in modern English to efficiently specify extended durations.

Structure: hours (unit of time) + long (extended duration) - hours: From Old English ūr, ultimately from Latin hōra (hour, time, season). Functions as a plural noun indicating a unit of time. - long: From Old English lang, long (having great linear extent, lasting a great while), from Proto-Germanic langaz. Functions as an adjective meaning of extended duration.