We use this term for wall clocks of diameters from 18” and up, clocks which are perfect for decorating and filling those walls where… you’re just not sure you want a painting.  They’re also great in the higher elevations of cathedrals spaces at home.  Sizes go up to 40” though most we sell are an easy-to-place 23”.  Favorite brands include Howard Miller and the Timeworks designs.