The compound adjective 'two-week-old' is a modern English formation built from three native Germanic elements. The numeral 'two' originates from the fundamental Indo-European root for duality, which is preserved across many languages. The concept 'week' derives from a Germanic base implying a cycle or sequence, reflecting the structured division of time. The suffix '-old', from a root meaning 'grown', evolved to specify the duration of existence. When combined, these morphemes create a transparent and logical descriptor for something that has existed for a fortnight, showcasing English's capacity for precise, compound modification.

Structure: two (number) + week (time period) + old (having existed for a specified time) - two: From Old English 'twā', of Germanic origin; related to Dutch 'twee' and German 'zwei', from an Indo-European root shared by Latin 'duo' and Greek 'duo'. Functions as a cardinal number. - week: From Old English 'wice', of Germanic origin; related to Dutch 'week' and German 'Woche', from a base probably meaning 'sequence, series'. Functions as a noun denoting a period of seven days. - old: From Old English 'ald', of Germanic origin; related to Dutch 'oud' and German 'alt', from an Indo-European root meaning 'grown-up, adult'. Functions as an adjective indicating age or duration.