The word 'waterway' is a transparent compound formed from two native English roots. 'Water' descends from the Proto-Germanic watōr, itself from the Proto-Indo-European wódr̥, a neuter noun for water. 'Way' traces back to Proto-Germanic wegaz, from the PIE root weǵh- meaning "to go, transport." The compound's logic is perfectly literal: a "water-path" or a route for travel and transport that is made of or exists on water. This straightforward combination reflects a common pattern in English for naming geographical and navigational features, where the modern meaning is a direct and concrete extension of the ancient roots' core senses.

Structure: water (liquid H₂O) + way (path) water: From Old English 'wæter', of Proto-Germanic origin; related to Dutch 'water' and German 'Wasser'. Functions as the core semantic root denoting the liquid substance. way: From Old English 'weg', of Germanic origin; related to Dutch 'weg' and German 'Weg'. Functions as a noun-forming element indicating a path, route, or course.