Kentucky (US: kən-TUK-ee, UK: ken-), officially the Commonwealth of Kentucky, is a landlocked state in the Southeastern region of the United States. Kentucky borders Illinois, Indiana, and Ohio to the north, West Virginia to the northeast, Virginia to the east, Tennessee to the south, and Missouri to the west. Its northern border is defined by the Ohio River. Its capital is Frankfort and its largest city is Louisville. As of 2020, the population was approximately 4.5 million.

Kentucky was admitted into the Union as the 15th state on June 1, 1792, splitting from Virginia in the process. It is known as the "Bluegrass State", a nickname based on Kentucky bluegrass, a species of green grass introduced by European settlers for the purpose of grazing in pastures, which has supported the thoroughbred horse industry in the center of the state.

Historically, Kentucky had excellent farming conditions, which led to the development of large tobacco plantations similar to those in Virginia and North Carolina in the central and western parts of the state that utilized enslaved labor during the Antebellum South and Civil War periods. Kentucky ranks fifth nationally in goat farming, eight in beef cattle production, and 14th in corn production. While Kentucky has been a long-standing major center for the tobacco industry, the state's economy has diversified in multiple non-agricultural sectors, including auto manufacturing, energy fuel production, and medical facilities. The state ranks 4th among US states in the number of automobiles and trucks assembled. Kentucky is one of several states considered a part of the Upland South.

The state is home to the world's longest cave system in Mammoth Cave National Park, the greatest length of navigable waterways and streams in the contiguous United States, and the two largest artificial lakes east of the Mississippi River. Cultural aspects of Kentucky include horse racing, bourbon, moonshine, coal, My Old Kentucky Home State Park, automobile manufacturing, tobacco, southern cuisine, barbecue, bluegrass music, college basketball, Louisville Slugger baseball bats, Kentucky Fried Chicken, and the Kentucky Colonel.