정체를 알 수 없는 비행 물체로, 흔히 외계 생명체의 비행선으로 여겨지는 것.
An unidentified flying object, typically one that is suspected of being of extraterrestrial origin.
예문:
"The witness described the UFO as a glowing disk moving at incredible speeds."
"Military radar picked up a UFO that vanished as quickly as it had appeared."
"The documentary explores various theories regarding UFO sightings in the 1950s."