reservoir

American  

[rez-er-vwahr, -vwawr, -vawr, rez-uh-] / ˈrɛz ərˌvwɑr, -ˌvwɔr, -ˌvɔr, ˈrɛz ə- /

noun

• reservoirs
  plural

1. a natural or artificial place where water is collected and stored for use, especially water for supplying a community, irrigating land, furnishing power, etc.

2. a receptacle or chamber for holding a liquid or fluid.

3. Geology. pool16

4. Biology. a cavity or part that holds some fluid or secretion.

5. a place where anything is collected or accumulated in great amount.

   Synonyms:

   stockpile, fund, pool, store, hoard

6. a large or extra supply or stock; reserve.

   a reservoir of knowledge.

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reservoir British  

/ ˈrɛzəˌvwɑː /

noun

1. a natural or artificial lake or large tank used for collecting and storing water, esp for community water supplies or irrigation

2. a receptacle for storing gas, esp one attached to a stove

3. biology a vacuole or cavity in an organism, containing a secretion or some other fluid

4. anatomy another name for cisterna

5. a place where a great stock of anything is accumulated

6. a large supply of something; reserve

   a reservoir of talent

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reservoir Scientific  

/ rĕz′ər-vwär′ /

1. A natural or artificial pond or lake used for the storage of water.

2. An underground mass of rock or sediment that is porous and permeable enough to allow oil or natural gas to accumulate in it.

3. An organism that is the host for a parasitic pathogen or that directly or indirectly transmits a pathogen to which it is immune.

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Other Word Forms

Noun Inflected Forms

• reservoirs
  plural

Etymology

Origin of reservoir

1680–90; < French réservoir, equivalent to réserv ( er ) to reserve + -oir -ory ²

Explanation

The word reservoir refers to a place where large amounts of water get stored. It can also be used to describe great amounts of other things, such as when you refer to a trivia expert as a reservoir of useless knowledge. The word reservoir comes from the French réservoir, which further derives from the Old French reserver, meaning "to reserve." Knowing this, it makes sense that the meaning evolved into a place, either man-made or natural, where water is stored or "reserved," usually for distribution for drinking, irrigating, and generating power. Remembering the related word reserve might also help in both the spelling and pronunciation of the word, as reserve is spelled (and pronounced) with "er," the same as "reservoir."

Example Sentences

See Examples For:

reservoir reservoirs

The area is renowned for being one of the most picturesque in Los Angeles, boasting a beautiful reservoir with a large walking loop around the outside, as well as multiple boutique stores and restaurants.

From MarketWatch ● Aug. 21, 2026

If reservoir levels continue to fall, it allows for larger mandatory water cuts of up to 3 million acre-feet per year in California, Arizona and Nevada — as much as 40% of the combined allotments.

From Los Angeles Times ● Aug. 21, 2026

As the water level at Lake Mead has plunged to a historic low, more human remains are emerging from the depths of the nation’s largest reservoir.

From Los Angeles Times ● Aug. 19, 2026

Then comes river flow drought, where river levels fall, and, finally, if dry conditions persist for long enough, groundwater and reservoir levels decline, leading to the most serious impacts.

From BBC ● Aug. 18, 2026

I touched his fancy watch that he never wore and the extra laces for his sneakers that would never run around the reservoir again.

From "Extremely Loud and Incredibly Close" by Jonathan Safran Foer

Drought will only be declared as over once reservoirs, rivers and groundwater stocks are replenished.

From BBC ● Aug. 21, 2026

And in the last quarter-century, relentless drought intensified by climate change has sapped the river’s flow and left its reservoirs severely depleted.

From Los Angeles Times ● Aug. 18, 2026

The Trump administration has released a 10-year plan for cutting water use to prop up the Colorado River’s reservoirs, which have fallen to a record low.

From Los Angeles Times ● Aug. 18, 2026

The two largest reservoirs in the United States have fallen to record lows as a severe drought grips the country's West, according to data released over the weekend.

From Barron's ● Aug. 17, 2026

He spent years traveling across central Africa in search of the reservoirs of Ebola and Marburg viruses.

From "The Hot Zone" by Richard Preston

Related Words

• basin
• cistern
• container
• lake
• pond
• pool
• reserve
• source
• stockpile
• storage
• supply
• tank