Tennessee bourbon is an alcoholic beverage from the Tennessee region on Earth. It is a variation on Kentucky bourbon -- straight whiskey that has been distilled from a fermented grain mash, a corn (maize) mixture, and aged in a wooden barrel.
In 2296, Leonard McCoy jokingly told Spock that he would not "waste" Tennessee bourbon on him, offering him Romulan ale instead. (TOS novel: Vulcan's Forge)