To run the wort from the mash tun. From the German word to clarify. A lauter tun is a separate vessel to do this job. It uses a system of sharp rakes to achieve a very intensive extraction of malt sugars.

v. To strain spent grain from the water into which the grain's sugars have been extracted by the mashing process.

To strain or separate. Lautering acts to separate the wort from grain via filtering and sparging.

From the German word to clarify. To run the wort from the mash tun using a system of sharp rakes to extract the malt sugars.