Extraterrestrial being and Hypothetical creature

Extraterrestrial being noun - A form of life assumed to exist outside the Earth or its atmosphere.

Hypothetical creature and extraterrestrial being are semantically related. In some cases you can use "Hypothetical creature" instead a noun phrase "Extraterrestrial being".

Hypothetical creature noun - A creature that has not been observed but is hypothesized to exist.

Extraterrestrial being and hypothetical creature are semantically related. Sometimes you can replace phrase "Extraterrestrial being" with "Hypothetical creature", this phrases are similar.