oro-¹

Mountains.

Greek oros, mountain.

Terms include orogeny (adjective orogenic), a process in which a section of the earth's crust is folded and deformed by lateral compression to form a mountain range; the adjective orographic refers to mountains, especially as regards their position and form; and an orocline (Greek klinein, to slope) is an orogenic system in which rocks have been flexed into a horseshoe shape.