köken: Sound shift from older クセノン (kusenon), itself a borrowing from German Xenon. Listed in some references as a borrowing from English xenon. An English derivation would have been borrowed with the initial xe- rendered as ゼ (ze) or ジ (ji), whereas クセ (kuse) and キセ (kise) instead point to Dutch or German as the source language.
köken: Borrowed from either German Xenon, French xénon or Russian ксено́н (ksenón), from Ancient Greek ξένον (xénon), neuter of ξένος (xénos, “foreign, strange”).
Etimoloji
From Ancient Greek ξένον (xénon), neuter of ξένος (xénos, “foreign, strange”).