Terminology
Today, nuclear-powered warships and submarines, although powered by steam-driven turbines, are not usually referred to as steamships.
Screw-driven steamships generally carry the ship prefix "SS" before their names, meaning 'Steam Ship' (or 'Screw Steamer' i.e. 'screw-driven steamship', or 'Screw Schooner' during the 1870s and 1880s, when sail was also carried), paddle steamers usually carry the prefix "PS" and steamships powered by steam turbine may be prefixed "TS" (turbine ship). The term steamer is occasionally used, out of nostalgia, for diesel motor-driven vessels, prefixed "MV".
Read more about this topic: Steamboat