What is "maderisation"

Maderisation (also maderization) is a process that involves the heating and oxidization of a wine. The term is named after the process used in the production of Madeira wine, where it occurs while the wine is in cask. The resulting wine darkens in color and acquires a Sherry-like character. Outside Madeira wine, it is generally seen as a wine fault, but is desirable in the case of certain dessert wines where it occurs over the course of long bottle aging.