origin: from Ancient Greek (xenos) "foreign, strange" + biology (bios, "life" and -logia, "study")
1. the study of the biology of alien life forms (a branch of astrobiology).
It's important to note a related word, exobiology, whereupon a fine line shall be drawn. Exobiology examines life outside of planet Earth, as well as the effects of extraterrestrial environments on living things (like humans) -- whereas xenobiology takes into account that not only could alien life be among us now, but could hypothetically be synthesized in the future, and therefor can be clarified as, "biology based on foreign chemistry"*.
REMINDER- annular solar eclipse today!