9 letters · 12 points in Scrabble
noun a large or extra supply of something
noun lake used to store water for community use
noun tank used for collecting and storing a liquid (as water or oil)
originFrom French réservoir (“collection place”) (fig.), réservoir (“storehouse”) (lit.). in turn from French réserver (“to reserve, keep”).
Etymology from Wiktionary, CC BY-SA 3.0