Big Coppitt Key is a census-designated place and an unincorporated community in Monroe County, Florida, on an island of the same name in the lower Florida Keys. The CDP also includes the neighboring islands of Geiger Key and Shark Key. As of the 2000 census, it had a total population of 2,595. The name is said to be a derivation of the old English word "coppice", meaning thicket. According to A.D.