New Delhi: Unidentified flying object, commonly abbreviated as UFO, is the popular term for any aerial phenomenon whose cause cannot be easily or immediately identified by the observer.
The United States Air Force, which coined the term in 1952, initially defined UFOs as those objects that remain unidentified after scrutiny by expert investigators, though the term UFO is often used more generally to describe any sighting unidentifiable to the reporting observers.
Popular culture frequently takes the term UFO as a synonym for alien spacecraft. Cults have become associated with UFOs, and mythology and folklore have evolved around the phenomenon.
Some investigators now prefer to use the broader term unidentified aerial phenomenon, to avoid the confusion and speculative associations that have become attached to UFO.
Another widely known acronym for UFO in Spanish, French, Portuguese and Italian is OVNI.