selen(o)-¹

The moon.

Greek selēnē, moon.

Selenography is—lunar geography; selenology is the scientific study of the moon; something selenocentric has the moon as its centre; selenodesy (Greek daiein, to divide) is the branch of mathematics dealing with the shape and area of the moon or large parts of it, the lunar equivalent of geodesy; selenite is either a colourless and transparent crystalline form of gypsum (so called because it was thought to wax and wane with the moon), or a supposed inhabitant of the moon (but see seleno‑²); molar teeth that are selenodont have crescent-shaped ridges on the grinding surfaces, characteristic of ruminants.