The Collaborative International Dictionary
Panspermist
Panspermatist \Pan*sper"ma*tist\, Panspermist \Pan"sper`mist\, n. (Biol.) A believer in panspermy; one who rejects the theory of spontaneous generation; a biogenist.
Wiktionary
panspermist
n. An advocate of panspermism; one who believes that life on Earth originated in outer space.
Usage examples of "panspermist".
The arks launched before the Crash are still en route and if Eveline Hywood and her panspermist friends are right, the galaxy must be full of worlds that have ecospheres of their own, including many that are ripe for colonization.