eighty-year-old

The compound "eighty-year-old" is a modern English construction built from native Germanic elements. Its first component, "eighty," originates from the Old English 'eahtatig', a transparent formation meaning "eight tens," which itself descends from the Proto-Germanic 'ahtōu tigiwiz'. The core units "year" and "old" are similarly ancient, with "year" (Old English 'gēar') tracing to a Proto-Indo-European root meaning "year, summer," and "old" (Old English 'eald') relating to concepts of growth and adulthood. The hyphenated structure follows a productive English pattern for forming compound adjectives and nouns that specify age, logically combining a numerical quantity, a temporal unit, and a state of being to precisely denote an octogenarian.

Structure: eighty (number) + year (time unit) + old (aged) eighty: From Old English 'eahtatig', a compound of 'eahta' (eight) and '-tig' (group of ten). A cardinal number denoting eight tens. year: From Old English 'gēar', meaning a period of twelve months or the cycle of seasons. old: From Old English 'eald', meaning advanced in age, having existed for a long time.