the.com/water cycle

means The continuous movement of water on, above, and below Earth's surface, as it evaporates into vapor, condenses into clouds, falls as precipitation, and eventually makes its way back to the sea to start over.

from 'Cycle' comes from the Greek 'kyklos,' meaning 'circle' or 'wheel' — the same root that gives us 'bicycle' and 'encyclopedia.' 'Water' traces back through Old English 'wæter' to a very old Proto-Indo-European root, 'wod-/wed-,' shared by words like the Russian 'voda' (as in vodka) and the Greek 'hydor' (as in hydrogen). The phrase itself is a modern scientific pairing, not an ancient one — naturalists only began mapping evaporation, condensation, and runoff into one continuous loop as a formal concept in the 1800s, once the mechanics of rainfall and rivers were properly understood.