Noun

That portion of precipitation or irrigation on an area which does not infiltrate or evaporate, but instead is discharged from the area.

Dissolved chemicals, etc, included in such water.

The runoff of nitrates is poisoning the lake.

A second or further round of an indecisive election, after other candidates (often all but the last two) have been eliminated,

There will now be a runoff as neither front runner received more than 50% of the vote.

* {{quote-news

, year=2012 , date=April 23 , author=Angelique Chrisafis , title=François Hollande on top but far right scores record result in French election , work=the Guardian citation , page= , passage= It is one of the left's best ever results and will raise momentum for next month's final runoff where only the two candidates will compete against each other.}}

Noun

(en noun)

(uncountable) The result of having been being worn away or eroded, as by a glacier on rock or the sea on a cliff face.

* 2012 , (George Monbiot), (Guardian Weekly) , August 24, p.20

Even second-generation in the ground.

(uncountable) The changing of a surface by mechanical action, friction, thermal expansion contraction, or impact.

(uncountable) Destruction by abrasive action of fluids.

(mathematics, image processing) One of two fundamental operations in (morphological image processing) from which all other morphological operations are derived.

(dentistry) Loss of tooth enamel due to non-bacteriogenic chemical processes.

(medicine) A shallow ulceration or lesion, usually involving skin or epithelial tissue.