1) Brewing term 
(kroy-zen) Used to refer to the foamy head that builds on top of the beer during fermentation. Also an advanced method of priming.
(from the article `beer`) A slow secondary fermentation of residual or added sugar (called primings) or, in lager brewing, the addition of actively fermenting wort (called ...
Krausen is the foamy and bubbly head that forms on top of beer during primary fermentation. As yeast ferments the sugars in a beer, it creates a great deal of CO2. The Krausen is formed as the CO2 rises to the top of the beer mixing with proteins, yeast and residues in the beer forming a tall layer of yeast saturated bubbles. Krausening is also a t...
A method to carbonate beer in which wort is added to the fermented/finished beer to carbonate. (wiki)