[rez-er-vwahr, -vwawr, -vawr, rez-uh-]


a natural or artificial place where water is collected and stored for use, especially water for supplying a community, irrigating land, furnishing power, etc.
a receptacle or chamber for holding a liquid or fluid.
Geology. See under pool1(def 6).
Biology. a cavity or part that holds some fluid or secretion.
a place where anything is collected or accumulated in great amount.
a large or extra supply or stock; reserve: a reservoir of knowledge.

Origin of reservoir

1680–90; < French réservoir, equivalent to réserv(er) to reserve + -oir -ory2

Synonyms for reservoir




a small body of standing water; pond.
a still, deep place in a stream.
any small collection of liquid on a surface: a pool of blood.
a puddle.
a subterranean accumulation of oil or gas held in porous and permeable sedimentary rock (reservoir).

verb (used without object)

to form a pool.
(of blood) to accumulate in a body part or organ.

verb (used with object)

to cause pools to form in.
to cause (blood) to form pools.


of or for a pool: pool filters.
taking place or occurring around or near a pool: a pool party.

Origin of pool

before 900; Middle English; Old English pōl; cognate with Dutch poel, German Pfuhl Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for reservoirs

Contemporary Examples of reservoirs

Historical Examples of reservoirs

  • Further up the brook were two other dams, used as reservoirs.


    Samuel T. Pickard

  • In a moment the very heavens seemed to be emptying their reservoirs.

    The Golden Woman

    Ridgwell Cullum

  • There is no reason to doubt that these reservoirs were the works of Solomon.


    Benjamin Disraeli

  • Nor that the queen was seen waiting outside the gate at the reservoirs?

    The Queen's Necklace

    Alexandre Dumas pre

  • They were out of the carriage now and walking toward the reservoirs.

    Sunny Boy in the Big City

    Ramy Allison White

British Dictionary definitions for reservoirs



a natural or artificial lake or large tank used for collecting and storing water, esp for community water supplies or irrigation
a receptacle for storing gas, esp one attached to a stove
biology a vacuole or cavity in an organism, containing a secretion or some other fluid
anatomy another name for cisterna
a place where a great stock of anything is accumulated
a large supply of something; reservea reservoir of talent

Word Origin for reservoir

C17: from French réservoir, from réserver to reserve




a small body of still water, usually fresh; small pond
a small isolated collection of liquid spilt or poured on a surface; puddlea pool of blood
a deep part of a stream or river where the water runs very slowly
an underground accumulation of oil or gas, usually forming a reservoir in porous sedimentary rock

Word Origin for pool

Old English pōl; related to Old Frisian pōl, German Pfuhl




any communal combination of resources, funds, etca typing pool
the combined stakes of the betters in many gambling sports or games; kitty
commerce a group of producers who conspire to establish and maintain output levels and high prices, each member of the group being allocated a maximum quota; price ring
finance, mainly US
  1. a joint fund organized by security-holders for speculative or manipulative purposes on financial markets
  2. the persons or parties involved in such a combination
any of various billiard games in which the object is to pot all the balls with the cue ball, esp that played with 15 coloured and numbered balls; pocket billiards

verb (tr)

to combine (investments, money, interests, etc) into a common fund, as for a joint enterprise
commerce to organize a pool of (enterprises)
Australian informal to inform on or incriminate (someone)
See also pools

Word Origin for pool

C17: from French poule, literally: hen used to signify stakes in a card game, from Medieval Latin pulla hen, from Latin pullus young animal
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for reservoirs



1680s, "a place where something tends to collect," originally figurative, from French réservoir "storehouse," from Old French reserver "to reserve" (see reserve (n.)). Specific meaning "artificial basin to collect and store a large body of water" is from 1705.



"small body of water," Old English pol "small body of water; deep, still place in a river," from West Germanic *pol- (cf. Old Frisian and Middle Low German pol, Dutch poel, Old High German pfuol, German Pfuhl). As a short form of swimming pool it is recorded from 1901. Pool party is from 1965.



game similar to billiards, 1848, originally (1690s) a card game played for collective stakes (a "pool"), from French poule "stakes, booty, plunder," literally "hen," from Old French poille "hen, young fowl" (see foal (n.)).

Perhaps the original notion is from jeu de la poule, supposedly a game in which people threw things at a chicken and the player who hit it, won it, which speaks volumes about life in the Middle Ages. The notion behind the word, then, is "playing for money." The connection of "hen" and "stakes" is also present in Spanish polla and Walloon paie.

Meaning "collective stakes" in betting first recorded 1869; sense of "common reservoir of resources" is from 1917. Meaning "group of persons who share duties or skills" is from 1928. From 1933 as short for football pool in wagering. Pool shark is from 1898. The phrase dirty pool "underhanded or unsportsmanlike conduct," especially in politics (1951), seems to belong here now, but the phrase dirty pool of politics, with an image of pool (n.1) is recorded from 1871 and was in use early 20c.



"to make a common interest, put things into a pool," 1871, from pool (n.2). Related: Pooled; pooling.



of liquid, "to form a pool or pools," 1620s, from pool (n.1).

Online Etymology Dictionary, © 2010 Douglas Harper

reservoirs in Medicine




A collection of blood in any region of the body due to dilation and retardation of the circulation in capillaries and veins.


[rĕzər-vwär′, -vwôr′, -vôr′]


A fluid-containing sac or cavity.
An organism or a population that directly or indirectly transmits a pathogen while being virtually immune to its effects.
A large or extra supply; a reserve.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

reservoirs in Science



A natural or artificial pond or lake used for the storage of water.
An underground mass of rock or sediment that is porous and permeable enough to allow oil or natural gas to accumulate in it.
An organism that is the host for a parasitic pathogen or that directly or indirectly transmits a pathogen to which it is immune.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.