/si lee"nee euhm/ , n. Chem.
a nonmetallic element chemically resembling sulfur and tellurium, occurring in several allotropic forms, as crystalline and amorphous, and having an electrical resistance that varies under the influence of light. Symbol: Se; at. wt.: 78.96; at. no.: 34; sp. gr.: (gray) 4.80 at 25°C, (red) 4.50 at 25°C.
[ selén ( e ) moon + NL -ium -IUM; named in allusion to its similarity to TELLURIUM ]