Reservoir /(rĕz"ẽr*vwôr`; 277)/

Res·er·voir

Reservoir

n.
  1. A place where anything is kept in store; especially, a place where water is collected and kept for use when wanted, as to supply a fountain, a canal, or a city by means of aqueducts, or to drive a mill wheel, or the like.
  2. A small intercellular space, often containing resin, essential oil, or some other secreted matter. (Bot.)
  3. A large quantity of infectious microorganisms resident in animals other than man, potentially capable of being transmitted to humans. (Med.)
  4. a large quantity of infectious microorganisms or parasites resident in animals other than man, potentially capable of being transmitted to humans; especially, such organisms in animals where they do little or no harm to the host. (Med.)
  5. A large supply or stock of anything which may be rapidly put to use; a reserve.

Phrases & Compounds
Receiving reservoir
a principal reservoir into which an aqueduct or rising main delivers water, and from which a distributing reservoir draws its supply.