a trivalent chemical element, one of the rare-earth elements: symbol, Er; at. no., 68
See erbium in American Heritage Dictionary 4
(ûrˈbē-əm)
noun Symbol Er
A soft, malleable, silvery rare-earth element, used in metallurgy and nuclear research and to color glass and porcelain. Atomic number 68; atomic weight 167.26; melting point 1,497°C; boiling point 2,900°C; specific gravity 9.051; valence 3. See Table at element.