English word xeno- comes from Ancient Greek ξένον

Detailed word origin of xeno-

Dictionary entry	Language	Definition
ξένον	Ancient Greek (grc)
xeno-	English (eng)	From a foreign place, as in xenolith. Having to do with foreigners, as in xenophilia, or more commonly, xenophobia.. Relating to strangers or strangeness, as in xenodochy or xenomenia.