Main Entry: se·le·ni·um

Pronunciation: \sə-ˈlē-nē-əm\

Function: noun

Etymology: New Latin, from Greek selēnē moon, from selas brightness

Date: 1818

: a photosensitive element that occurs in both crystalline and amorphous forms, is obtained chiefly as a by-product in copper refining, and is used especially in glass, semiconductor devices, and alloys — see element table