The English word 'week' descends from the Old English 'wice' or 'wicu', which itself originated from the Proto-Germanic 'wikōn'. This Germanic root is thought to be connected to the concept of a "turn" or "succession", likely referring to the regular cycle of days. The deeper Proto-Indo-European root is hypothesized to be 'weik-', meaning "to bend, wind, turn", linking the abstract idea of a recurring cycle to a more concrete physical action. The standardization of the seven-day cycle is a later cultural development, with the ancient Germanic term for this period being firmly established long before its adoption.

The word 'week' is a simplex word of Germanic origin. It functions as a single, unanalyzable morpheme in modern English.