Words: ancient astronaut hypothesis paleocontact hypothesis
Part of speech: n
Definition: a pseudo-scientific hypothesis that posits that intelligent extraterrestrial beings have visited Earth and made contact with humans in antiquity and prehistory.
Example: Sagan argued that while many legends, artifacts and purported out-of-place artifacts were cited in support of ancient astronaut theories, "very few require more than passing mention" and could be easily explained with more conventional theories.