unidentified flying object

noun3

1. •
   Anything not readily explainable appearing to move through or be suspended in the air.

   • The lights seen over the city last night, originally termed unidentified flying objects, turned out to be spotlights from a car dealership reflecting on low clouds.
2. •
   Such things as seem to be discrete objects and comparable to aircraft.

   • She said that the unidentified flying object then turned around, zoomed to a higher altitude, and loitered briefly before speeding off.
3. •
   (informal) An alien spacecraft.

   • He said that the strange beings then took him aboard their unidentified flying object and examined his body.