overflow
Americanverb (used without object)
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to flow or run over, as rivers or water.
After the thaw, the river overflows and causes great damage.
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to have the contents flowing over or spilling, as an overfull container.
Stop pouring or your glass is going to overflow.
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to pass from one place or part to another as if flowing from an overfull space.
The population overflowed into the adjoining territory.
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to be filled or supplied with in great measure.
a heart overflowing with gratitude; a region overflowing with orchards and vineyards.
verb (used with object)
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to flow over; flood; inundate.
The river overflowed several farms.
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to flow over or beyond (the brim, banks, borders, etc.).
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to cause to overflow.
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to flow over the edge or brim of (a receptacle, container, etc.).
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to fill to the point of running over.
noun
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an overflowing.
the annual overflow of the Nile.
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something that flows or runs over.
to carry off the overflow from a fountain.
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a portion crowded out of an overfilled place.
to house the overflow of the museum's collection in another building.
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an excess or superabundance.
an overflow of applicants for the job.
- Synonyms:
- glut, flood, plethora, surplus, overabundance
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an outlet or receptacle for excess liquid.
The tank is equipped with an overflow.
verb
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to flow or run over (a limit, brim, bank, etc)
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to fill or be filled beyond capacity so as to spill or run over
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to be filled with happiness, tears, etc
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(tr) to spread or cover over; flood or inundate
noun
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overflowing matter, esp liquid
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any outlet that enables surplus liquid to be discharged or drained off, esp one just below the top of a tank or cistern
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the amount by which a limit, capacity, etc, is exceeded
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computing a condition that occurs when numeric operations produce results too large to store in the memory space assigned to it
Other Word Forms
- overflowable adjective
- overflowingly adverb
- unoverflowing adjective
Etymology
Origin of overflow
before 900; Middle English overflowen, Old English oferflōwan. See over-, flow
Explanation
To overflow is to go beyond filling something with a liquid, so that it gushes over the edges. During heavy rainstorms, rivers sometimes overflow their banks and flood the surrounding land. Bathwater will overflow the tub if you don't turn the water off, and if you keep pouring coffee after your cup is full, it will also overflow. Literal overflowing involves liquid, but you can also use this verb to mean "fill a container" or "fill with feeling." So your arms can overflow with flowers, and your heart can overflow with happiness. The Old English root is oferfleow, "flood" or "inundate."
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Their findings suggest that inside lysosomes, this channel acts like an overflow valve, preventing the environment from becoming too acidic.
From Science Daily • Mar. 26, 2026
The ground is still wet from the storm last weekend, Parker said, making it hard for the new rain to be absorbed into the ground and causing streams to overflow.
From The Wall Street Journal • Mar. 20, 2026
Municipal meetings overflow with complaints, and local officials do what they can to push back.
From Slate • Feb. 12, 2026
Residents are being evacuated in trucks and horse-drawn carriages as overflow from the Loukkos River floods a neighbourhood in northern Morocco.
From Barron's • Jan. 30, 2026
Which makes Scoob’s Dad questions bubble up and overflow.
From "Clean Getaway" by Nic Stone
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
