The term scout was used by several European air forces up to the inter-war period to refer to a light reconnaissance aircraft, initially unarmed. The earliest air-to-air encounters were between opposing scouts, and generally involved little more than an exchange of pleasantries. Later the aircraft began to be armed, and in early Royal Flying Corps parlance a scout was a fighter aircraft, a usage often encountered in contemporary fiction such as the Biggles books. The two terms are used interchangeably from the latter years of World War I, the later term becoming dominant during the 1920s and the term Scout being dropped altogether. The Sopwith Pup was officially known as the Sopwith Scout (the popular name Pup, derived from its appearance of being a smaller version of the Sopwith 1 1/2 Strutter, was reportedly thought "undignified").
