From Proto-Baltic *kelH-, from Proto-Indo-European *kʷel(H)- (“to turn, to rotate, to move”) (whence also kult, q.v.). The original meaning of this word was therefore “moving place,” “movable member, organ.” Cognates include Lithuanian kelỹs, kẽlis, dialectal kialis, Old Church Slavonic колѣно (kolěno), Russian колено (koleno), and less likely Ancient Greek κῶλον (kôlon, “organ”), κωλῆ (kōlê, “femoral bone”).