The compound adjective "two-week" is a transparent and relatively modern formation in English, created by directly combining two native Germanic elements. The numeral "two" derives from the ancient Proto-Indo-European root dwóh₁, which is the source for the number two across many languages, reflecting a fundamental concept of duality. The word "week" originates from a Germanic root concerning a cycle or sequence, specifically the seven-day cycle established in ancient times. The logic of the compound is purely descriptive, with the numeral quantifying the noun to denote a duration spanning precisely that number of weeks, showcasing English's capacity for straightforward, analytical word formation.

Structure: two (numeral) + week (noun) - 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 dyo. Functions as a numeral quantifying the noun. - week: From Old English wice, wicu, of Germanic origin; related to Dutch week and German Woche, from a base probably meaning "sequence, series". Functions as the noun unit of time being modified.