The compound 'twenty-three-year-old' is a modern English construction built from native Germanic elements. Its components trace back to the fundamental Proto-Indo-European concepts of number, time, and growth. The numeral 'twenty-three' combines roots for 'two' and 'three' with a suffix denoting a decade count, while 'year' originates from a term for a seasonal cycle. The adjective 'old' stems from the notion of growth and maturity. The hyphenated structure logically assembles these parts to create a single lexical unit that precisely specifies an age, transitioning from a literal description of elapsed years to a standard demographic classifier.

Structure: twenty (20) + three (3) + year (period of time) + old (having age) - twenty: From Old English twēntig, meaning 'group of twenty', from twēn- (two) + -tig (group of ten). Functions as a cardinal number. - three: From Old English þrīe, from Proto-Germanic þrīz, from Proto-Indo-European tréyes. Functions as a cardinal number. - year: From Old English ġēar, from Proto-Germanic jērą, from Proto-Indo-European yóh₁r̥ (year, season). Functions as a noun denoting a time unit. - old: From Old English eald, from Proto-Germanic aldaz, from Proto-Indo-European h₂el- (to grow, nourish). Functions as an adjective meaning 'having existed for a long time'.