(; German: "His Majesty's Ship", abbreviated to S.M.S. or SMS) was the ship prefix used by the Prussian Maritime Enterprise (Seehandlung), the Prussian Navy, the Imperial German Navy (Kaiserliche Marine) and the Austro-Hungarian Navy.
It was sometimes also abbreviated to S.M. or SM (for Seiner Majestät) when a ship was mentioned by class, such as S.M. Kleiner Kreuzer Emden ("His Majesty's Light Cruiser Emden").