<P> Naval prefixes came into use as abbreviations for longer titles , such as `` His / Her Majesty 's Ship '' in the British Royal Navy , abbreviated `` H.M.S. '' and then `` HMS '' . Earlier uses often included the type of vessel , as for instance `` U.S.F. '' ( `` United States Frigate '' ) for frigates of the United States Navy , that were eliminated by President Theodore Roosevelt 's Executive order of 1907 making `` United States Ship '' ( USS ) the standard for the Navy 's commissioned ships while in commission . In the United States Navy that prefix officially only applies while the ship is in active commission , with only the name used before or after a period of commission and for all vessels `` in service '' rather than commissioned status . Today the common practice is to use a single prefix for all warships of a nation 's navy , and other prefixes for auxiliaries and ships of allied services , such as coast guards . </P>
what does ss stand for on naval ships
`` United States Ship '' ( USS )