Runoff

Noun

1. That portion of precipitation or irrigation on an area which does not infiltrate or evaporate, but instead is discharged from the area.<!-- That which is lost without entering the soil is called [[surface runoff]]. That which enters the soil before reaching a stream channel is called ground water runoff or seepage flow from ground water. (In [[soil science]] runoff usually refers to the water lost by surface flow; in [[geology]] and hydraulics runoff usually includes both surface and subsurface flow.)-->
2. Dissolved chemicals, etc, included in such water.

   "The runoff of nitrates is poisoning the lake."

3. A second or further round of a competition, after other competitors (often all but the last two) have been eliminated.
4. 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."