The term 'PREFIX WITH -STAT' can be used to describe three different words: Rheo, Aero, and Hemo. Rheo is a prefix meaning 'FLOW, ' Aero is a prefix meaning 'AIR, ' and Hemo is a prefix meaning 'BLOOD.' All three words are used to describe the state of something, such as the FLOW of a liquid or the AIR pressure in a room. By adding the suffix '-stat' to each of these words, they become Rheostat, Aerostat, and Hemostat, respectively. A Rheostat is a device used to regulate the FLOW of electricity, an Aerostat is a lighter-than-AIR craft, and a Hemostat is a device used to stop bleeding.