Cynthiana is a home rule-class city in Harrison County, Kentucky, in the United States. The population was 6,402 at the 2010 census. It is the seat of its county. The settlement developed on both sides of the South Fork of the Licking River. It was named after Cynthia and Anna Harrison, daughters of Robert Harrison, who had donated land to establish the town center. Harrison County, on the other hand, was named after Colonel Benjamin Harrison, an early settler in the area who had served as sheriff of Bourbon County.