res·​er·​voir | \ ˈre-zə-ˌvwär How to pronounce reservoir (audio) , -zər- How to pronounce reservoir (audio) , -ˌvwȯr How to pronounce reservoir (audio) also -ˌvȯi \

Definition of reservoir

1 : a place where something is kept in store: such 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 reservoir 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 usually without damaging its host

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Examples of reservoir in a Sentence

The pen has a large ink reservoir. Colleges and universities provide reservoirs of talent for job recruiters. She found the reservoirs of energy she needed to finish the job.
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Recent Examples on the Web The corps’ Fort Worth district – which covers a huge swath from Texarkana to Laredo – maintains some 25 reservoirs. Tom Benning, Dallas News, "Licensed gun owners in Texas may soon be able to carry at Lewisville Lake and other Army Corps of Engineer reservoirs," 8 May 2020 In an average year, 40% of Phoenix’s water comes from the Colorado River, 58% comes from reservoirs on the Salt and Verde rivers, and about 2% comes from groundwater. Ian James, azcentral, "Supercharged by climate change, ‘megadrought’ points to drier future in the West," 6 May 2020 Spring crappie season heating up on inland lakes, reservoirsWhen May arrivers around Northeast Ohio, the crappie begin to migrate to shallower structure, such as brush piles and weed beds, to spawn. cleveland, "Lake Erie charter fishing to resume in Ohio on May 12 with restrictions: Fishing Report," 30 Apr. 2020 These rivers flow into some of California’s biggest reservoirs, providing a large portion of the state’s water supply. Los Angeles Times, "Spring rain and snow fell short of miraculous for most of California," 30 Apr. 2020 In the greater Bay Area, San Pablo, Los Vaqueros, Del Valle, Chabot, Lafayette and Loch Lomond reservoirs are closed. Tom Stienstra,, "Clashing recreation rules vex Californians during coronavirus stay-at-home order," 24 Apr. 2020 It was taken on the sprawling 39,000-acre Lake Martin—a deep, clear, heavily fished reservoir on the Tallapoosa River in central Alabama. Bob Mcnally, Field & Stream, "14 of the Biggest Crappies of All TIme," 22 Apr. 2020 This is inconsistent with the special-reservoir hypothesis. John Timmer, Ars Technica, "There seems to be no pattern to where humans pick up new viruses," 22 Apr. 2020 That and subsequent agreements have allocated more water than the river can support in an average year, leading to chronic overuse and falling reservoirs. Ian James,, "How a trickle of water is breathing life into the parched Colorado River Delta," 19 Apr. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'reservoir.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of reservoir

1690, in the meaning defined at sense 1

History and Etymology for reservoir

French réservoir, from Middle French, from reserver

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Time Traveler for reservoir

Time Traveler

The first known use of reservoir was in 1690

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Statistics for reservoir

Last Updated

17 May 2020

Cite this Entry

“Reservoir.” Dictionary, Merriam-Webster, Accessed 27 May. 2020.

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More Definitions for reservoir


How to pronounce reservoir (audio) How to pronounce reservoir (audio) How to pronounce reservoir (audio)

English Language Learners Definition of reservoir

: a usually artificial lake that is used to store a large supply of water for use in people's homes, in businesses, etc.
: a place (such as a part of a machine) where a liquid is stored
: an extra supply of something


res·​er·​voir | \ ˈre-zər-ˌvwär How to pronounce reservoir (audio) \

Kids Definition of reservoir

: a place where something (as water) is kept in store for future use


res·​er·​voir | \ ˈrez-ə(r)v-ˌwär How to pronounce reservoir (audio) , -ə(r)v-ˌ(w)ȯr How to pronounce reservoir (audio) \

Medical Definition of reservoir

1 : a space (as an enlargement of a vessel or the cavity of a glandular acinus) in which a body fluid is stored
2 : 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 without regard to its pathogenicity for the reservoir rats are reservoirs of plague — compare carrier sense 1a

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