Definition - What does Nutty mean?
Nutty is a descriptor used to describe a wine which has been oxidized. The oxidation can occur at different times during fermentation or in the bottle with improper aging. These wines may have off aromas of old, decomposed fruit or stale nuts and oil. A nutty wine will not only have off aromas, but the taste will be off as well. It will also appear dull in color.
WineFrog explains Nutty
In some cases, "nutty" characteristics can occur in wine if it has had an extended fermentation or a stuck fermentation. The latter occurs when yeast dies off during the fermentation due to excess levels of alcohol or sugar. It can also happen when the yeast is lacking sufficient nutrients to continue the fermentation. It is a flaw more common with white wines than red. The same characteristic may also develop if the wine has not been stored in proper conditions. If the wine is oxidized, creating nutty characteristics, it is often due to a faulty cork or a cork which has dried out due to low levels of humidity over an extended period of time.