The compound noun 'water-bottle' is a transparent combination of two ancient nouns, each with a distinct lineage. 'Water' descends from the Proto-Indo-European root 'wodr̥-', a vital term for the fundamental liquid, which evolved directly into the Old English 'wæter'. 'Bottle' traces back to the Latin 'buttis', meaning a cask or vessel, which entered English via Old French, diminishing in form to specify a smaller, portable container. The modern compound logically and literally denotes a bottle intended for water, directly reflecting the core meanings of its constituent parts, which have remained remarkably stable through their respective linguistic journeys from PIE and Latin into contemporary English.

Structure: water (liquid) + bottle (container) water: From Old English 'wæter', of Proto-Germanic origin; related to Dutch 'water' and German 'Wasser'. Functions as the defining noun, specifying the liquid content. bottle: From Old French 'boteille', from late Latin 'butticula', a diminutive of Latin 'buttis' (cask). Functions as the head noun, specifying the type of container.