This term can have different meanings:
Term for the taste or consistency of a wine in the context of a wine address or wine evaluation. This is characterised by a high content of alcohol (ethanol) and glycerine and thus a full, oily taste. Sometimes such a wine can also have a little too little acidity. Related terms are meaty, oily and melting. However, the term should not be confused with fatty, which is considered the sixth flavour.
Common term in Austria for being highly intoxicated due to excessive alcohol consumption. Someone is "fat" or "he is in the fat'n", or, related to this, "in the oil". The verbal forms are "blunzenfett", "knüllefett", "rotznagelfett", "fett wie die russische Erde" or "fett wie eine Feldhaubitze". See also other expressions under intoxication; as well as under drinking culture.
I have great respect for the scope and quality of the wein.plus encyclopaedia. It is a unique place to go for crisp, sound information on terms from the world of wine.
Dr. Edgar Müller
Dozent, Önologe und Weinbauberater, Bad Kreuznach