reservoir

American  

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

noun

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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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

While reservoir performance and well construction divisions each posted a 6% drop in revenue, revenue within SLB’s production systems division surged 23%, boosted by the acquisition of technology provider ChampionX last year.

From Barron's • Apr. 24, 2026

While reservoir performance and well construction divisions each posted a 6% drop in revenue, revenue within SLB’s production systems division surged 23%, boosted by the acquisition of technology provider ChampionX last year.

From Barron's • Apr. 24, 2026

“It’s a failure to recognize that there is value to this community to have the reservoir full,” said Maryam Zar, head of the Palisades Recovery Coalition.

From Los Angeles Times • Apr. 22, 2026

Measures include shrinking how much water leaves that reservoir, which flows down the Colorado River into Lake Mead and supplies water to Southern California, Nevada and Arizona.

From Los Angeles Times • Apr. 21, 2026

We’d set up at the reservoir for good reason.

From "The Last Olympian" by Rick Riordan

Related Words

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