fifteen-year

The compound adjective "fifteen-year" is a modern English formation that follows a common Germanic pattern for creating descriptive terms related to age or duration. The first element, "fifteen," traces back to the Old English 'fīftīene', a transparent compound meaning "five and ten," which itself derives from the Proto-Germanic roots for those numbers. The second element, "year," originates from the Old English 'ġēar', a term of Proto-Germanic origin related to the concept of a cycle or season. When combined with a hyphen, these two morphemes function as a single attributive adjective, a grammatical construction that logically links a specific quantity of time (fifteen) with the cyclical unit of measurement (year) to describe either an age or a timespan.

Structure: fifteen (numeral) + year (noun) - fifteen: From Old English 'fīftīene', a compound of 'fīf' (five) and 'tīene' (ten). Its functional role is as a cardinal numeral. - year: From Old English 'ġēar', meaning a period of twelve months or the time taken by the earth to orbit the sun. Its functional role is as a noun denoting a unit of time.