Etymology tree Proto-Indo-European *sóh₂wl̥ Proto-Indo-European *sh₂wél(i)yos Proto-Hellenic *hāwélios Ancient Greek ἥλῐος (hḗlĭos) English helio- Proto-Indo-European *ḱent-der. Ancient Greek κέντρον (kéntron) Proto-Indo-European *-kos Ancient Greek -κός (-kós) Ancient Greek -ῐκός (-ĭkós) Ancient Greek κεντρικός (kentrikós)der. English -centric English heliocentric From helio- + -centric.