Extraterrestrial vessel and Flying saucer

Flying saucer and extraterrestrial vessel are semantically related In some cases you can use "Flying saucer" instead a noun phrase "Extraterrestrial vessel".

Flying saucer noun - An (apparently) flying object whose nature is unknown; especially those considered to have extraterrestrial origins.

Extraterrestrial vessel and flying saucer are semantically related in spaceship topic. You can use "Extraterrestrial vessel" instead a noun phrase "Flying saucer".