[res.er.voir] n [F reservoir, fr. MF, fr. reserver] (1690) 1: a place where something is kept in store: as a: an artificial lake where water is collected and kept in quantity for use b: a part of an apparatus in which a liquid is held c: supply, store "a large ~ of educated people"
2: an extra supply: reserve
3: an organism in which a parasite that is pathogenic for some other species lives and multiplies without damaging its host; also: a noneconomic organism within which a pathogen of economic or medical importance flourishes