From PIE *wodr — one of humanity's oldest words, hidden in 'whiskey' (water of life) and 'vodka' (little water).
A colourless, transparent, odourless liquid that forms the seas, lakes, rivers, and rain.
From Old English 'wæter' (water, the sea, a lake, any body of water), from Proto-Germanic *watōr (water), from Proto-Indo-European *wódr̥ (water — an r/n-stem noun, with the oblique stem *wed-). This is among the most securely and widely reconstructed PIE roots, appearing in virtually every branch of the family and demonstrating the extreme conservatism of this fundamental vocabulary item: Greek 'húdōr' (ὕδωρ → 'hydrate,' 'hydraulic,' 'hydrogen' — the water-former, 'hydrant,' 'hydra' — the many-headed water-serpent), Russian 'voda' (вода → 'vodka' — 'little water,' the diminutive), Irish Gaelic 'uisce' (→ 'whiskey,' from 'uisce beatha,' water of life — a direct translation of Medieval Latin 'aqua vitae'), Latin 'unda' (a wave → 'undulate,' 'inundate,' 'surround' — the ablaut variant *wed-), Sanskrit 'udán' (water, wave → 'udaka,' water), Hittite 'watar,' Gothic 'watō,' Tocharian 'wär' and 'war.' English has thus inherited three of its most consumed liquids from this single
'Water,' 'whiskey,' 'vodka,' 'otter,' and 'hydrate' all descend from PIE *wódr̥. Water is the thing itself. Whiskey is 'water of life' (Irish uisce beatha). Vodka is 'little water' (Russian). An otter is 'the water animal.' And hydrate comes from Greek húdōr. Five words, one ancient root, one molecule.