The word horizon derives from the Greek "ὁρίζων κύκλος" horízōn kýklos, "separating circle",[3] where "ὁρίζων" is from the verb ὁρίζω horízō, "to divide", "to separate",[4] which in turn derives from "ὅρος" (hóros), "boundary, landmark".[5]