Official definition from Jancis Robinson’s The Oxford Companion to Wine:
Decanting is the optional and controversial step in serving wine, involving pouring wine out of its bottle into another container called a decanter. The most obvious reason for decanting a wine is to separate it from any sediment that has formed in the bottle which not only looks unappetizing in the glass, but usually tastes bitter and/or astringent. …. Another, traditional but disputed, reason for decanting is to promote aeration and therefore encourage the development of the wine’s bouquet.

Official definition from Jancis Robinson’s The Oxford Companion to Wine:
Noble rot, also known as pourriture noble in French, Edelfaule in German, muffa in Italian, and sometimes simply as botrytis, is the benevolent form of botrytis bunch rot, in which the Botrytis cinerea fungus attacks ripe, undamaged white wine grapes and, given the right weather, can result in extremely sweet grapes which may look disgusting but have undergone such a complex transformation that they are capable of producing probably the world’s finest, and certainly the longest-living, sweet wines. Indeed, the defining factor of a great vintage for sweet white wine in areas specializing in its production is the incidence of noble rot.