Exoteric derives from Latin exōtericus, which is itself from Greek exoterikos, meaning "external," and ultimately from "exo, meaning "outside." "Exō" has a number of offspring in English, including "exotic," "exonerate," "exorbitant," and the combining form "exō-" or "ex-" (as in "exoskeleton" and "exobiology"). The antonym of "exoteric" is esoteric, meaning "designed for or understood by the specially initiated alone"; it descends from the Greek word for within," "esō."