arc [LME] A number of English words comes from Latin arcus ‘a bow, arch, or curve’, among them arc, arcade [L17th], and arch [ME]. Arc was originally a term for the path of the sun or other celestial objects from horizon to horizon. Given the shape of a bow for shooting arrows, it should not be surprising that archer [ME] has the same Latin source. Another meaning of arch, ‘chief or principal’ (as in archbishop [OE] or arch-enemy [M16th]), has a different origin, coming from Greek arkhos ‘a chief or ruler’. This Greek word can also be seen in anarchy [M16th], which literally means ‘the state of having no ruler’, in architect [M16th] from archi and tektōn ‘builder’, and archipelago [E16th] from archi and pelagos ‘sea’. This was originally used as a proper name for the Aegean Sea; the general sense ‘group of islands’ arose because the Aegean Sea is remarkable for its large numbers of islands.