Noun
mashout (uncountable)
(brewing) The step or process, in brewing beer, of raising the mash (e.g. by adding hot water to it) to a temperature around 75 °C or 170 °F, so as to stop the enzymatic conversion of starch to fermentable sugar and make the mash and wort more fluid.
Prior to lautering, the mash temperature may be raised to about convert (known as a mashout) to free up more starch and reduce mash viscosity. Source: Internet
The 1907 British Pharmaceutical Codex's instructions for making nutritional extract of malt do not include a mashout at the end of extraction, and include the use of lower mash temperatures than is typical with modern beer-brewing practices. Source: Internet