Motor Torpedo Boat (MTB) was the name given to fast torpedo boats by the Royal Navy and the Royal Canadian Navy. The 'motor' in the formal designation, referring to the use of petrol engines, was to distinguish them from the majority of other naval craft that used steam turbines or reciprocating steam engines.
The capitalised term is generally used for the Royal Navy (RN) boats and abbreviated to "MTB". During the Second World War, the US Navy boats were usually called by their hull classification symbol of "PT" (Patrol, Torpedo), and are covered under PT boat although the class type were still "motor torpedo boats".
German motor torpedo boats of the Second World War were called S-boote (Schnellboote, "fast boats") by the Kriegsmarine and "E-boats" by the Allies. Italian MTBs of this period were known as Motoscafo Armato Silurante ("MAS boats", torpedo armed motorboats). French MTBs were known as vedettes lance torpilles ("torpedo-launching fast boats"). Soviet MTBs were known as торпедные катеры (torpyedniye katyery; "torpedo cutters", often abbreviated as TKA). Romanian MTBs were known as vedete torpiloare ("torpedo fast boats").
After the end of the War in 1945, a number of the Royal Navy's MTBs were stripped and the empty hulls sold for use as houseboats.