The word UFO is an abbreviation which comes from the initial letters of the words ‘unidentified flying object’. A UFO is a mysterious object in the sky which can’t be explained by current scientific theories. UFOs are often associated with extraterrestrial beings: they’re believed to be the spaceships of the ‘little green men’ of science-fiction movies and stories.
According to the Oxford English Dictionary, the term ‘unidentified flying object’ goes back at least to the 1950s: it is recorded in 1953, in a book by the US aviator and writer Donald Keyhoe. The OED also gives a citation in 1956 by Edward Ruppelt, an officer in the USAF, stating that he’d invented the term as a more general one to replace the earlier description for such objects, flying saucer.
Strange objects in the sky were first named flying saucers in the 1940s: the first OED citation is from The Times, in 1947. They were so called because of an account by a US pilot, Kenneth Arnold, who stated in various newspaper and radio interviews of that year that he’d seen ‘saucer-like’ objects in the sky while he was flying past Mount Rainier. The media seemed to have quickly changed this to the snappier ‘flying saucer’ and so the term was born. By the time Ruppelt and his USAF colleagues were investigating reports of these sightings in the 1950s, it was clear that ‘saucer’ was too limited a description, since the objects in question were said to be of many different shapes: hence Ruppelt’s invention of ‘UFO’.
UFOs captured the public’s imagination and it wasn’t long before sightings were reported from all over the world. The study of UFOs became known as ufology (recorded in The Times Literary Supplement in 1959) and experts in the field were named ufologists about four years later, even though research in this area isn’t generally regarded as an academic discipline.