runoff

American  

[ruhn-awf, -of] / ˈrʌnˌɔf, -ˌɒf /

noun

1. something that drains or flows off, as rain that flows off from the land in streams.

2. a final contest held to determine a victor after earlier contests have eliminated the weaker contestants.

3. a deciding final contest held after one in which there has been no decisive victor, as between two contestants who have tied for first place.

4. Also called rundown.  a continual or prolonged reduction, especially in quantity or supply.

   a runoff in bank deposits; a sharp runoff in business inventories.

5. Stock Exchange. the final prices appearing on the ticker after the closing bell is rung for the trading day.

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Usage

What is a runoff? Runoff is liquid, especially water or rainwater, that flows off or drains away, as in The storm sewer could not hold all the runoff from the recent rains. This sense of runoff is often used in the context of environmental science. It often refers to water that flows into streams or back into the water supply rather than seeping into the ground. For example, when farm crops are watered, any water that is not absorbed into the ground and drains away instead is runoff. This term comes from the verb phrase run off, which can mean to drain or flow away, as in The wastewater runs off into the stream. An unrelated but also common meaning of runoff refers to a competition that determines a final winner after earlier contests have narrowed down the competitors. Similarly, it can refer to a contest held to determine a winner when the initial contest did not produce one, such as when two people tie. This sense of the word is especially used in the context of political elections. For example, a place may hold an election that features five candidates. After the election, the lowest vote-getter is removed and another election is held with the remaining candidates. This process is repeated until only two candidates are left. This final election, which finally decides the winner, is called a runoff. Less commonly, the verb run off can mean to decide a winner through a runoff, as in The final contest will be run off at the end of the month. Example: Due to the use of pesticides in many industrial farms, runoff becomes a major concern for local water supplies.

Etymology

Origin of runoff

1850–55, noun use of verb phrase run off; runoff ( def. 2, 3 ) see -off

Explanation

A runoff is an additional election that resolves an inconclusive one. If there’s a tie for class president, the candidates will need a runoff election to see who gets the job. A runoff is also an overflow of water. The physical type of runoff (also run-off) involves water or other liquids running off of something by overflowing and possibly flooding an area. If it rains and rains, the runoff from the soil could flow into a nearby pond. On the other hand, a runoff election means an initial vote did not result in a winner because it was tied or too close to call. A runoff election settles the matter, providing a final decision.

Example Sentences

Runoff from wildfire burn areas or bacteria such as E. coli could enter sinkholes connected to Roaring Springs Cave and reach the water supply.

From Science Daily • Jun. 2, 2026

Tulare Lake: Runoff from the wet winter brought water back to the Tulare Lake basin, submerging farmland in what was once the largest body of fresh water west of the Mississippi River.

From New York Times • Jun. 26, 2023

Runoff pools in shallow lakes, held back by rocks and debris.

From Reuters • Jun. 20, 2023

Runoff in the Kings River Watershed could be as high as 265% of average, while the Kern River watershed could see “an absurdly high 422% of average,” he said.

From Los Angeles Times • Apr. 5, 2023

Runoff is checked by a sod and less water is used by a sod in mid-summer, after it has been mowed, than by a heavy cover crop.

From Northern Nut Growers Association Report of the Proceedings at the Twenty-Fourth Annual Meeting Downington, Pennsylvania, September 11 and 12, 1933 by Northern Nut Growers Association

Related Words

• drainage