No one really knows when the phrase "tap dance" was first used -- perhaps as early as 1900 -- but it didn't appear in print until around1928.
Merriam-Webster defines it two ways. (1.) A step dance tapped out audibly by means of shoes with hard soles, or soles and heels, to which taps have been added.
By the mid-nineteenth century, African Americans had combined their footwork with Irish and British clogging steps to create a style called "Buck and Wing," which would eventually became Modern Tap Dance.
Tap dancing originated with African dancers in early America. When dancing, they would articulate rhythmic patterns through chugging, scooping, brushing and shuffling movements of the feet. These dancers came to be called Levee Dancers throughout the south. White performers copied many of these intricate steps and eventually the Shuffle Dance style found fame within the minstrel shows.
Tap Dance and Irish Clogging share deep roots.
Clog dances were often performed in wooden soled shoes. In Irish clog dancing, no thought is given to upper body movements. Almost rigid -- the shoulders and arms are kept motionless. This trait is also evident in the early, Black "Buck and Wing" style.
Reportedly, the most difficult of the Irish clogs are the Irish Jigs and Hornpipes. In some of these, the feet can tap the floor four or five times per second. Irish clog dancer, John "Jack" Diamond (1828 - 1850) was considered one of the greatest "Jig Dancers" of his day.
Modern tap dancing slowly evolved though the years 1900 to 1920.