say it: REZ-uhv-wahr
reservoir is a noun meaning "a large or extra supply of something". It carries 4 recorded senses.
lake used to store water for community use
tank used for collecting and storing a liquid (as water or oil)
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for reservoir come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.