a toxic nonmetallic element related to sulfur and tellurium; occurs in several allotropic forms; a stable grey metallike allotrope conducts electricity better in the light than in the dark and is used in photocells; occurs in sulfide ores (as pyrite)
"Engineers carefully analyzed the selenium extracted from local pyrite ores to manufacture efficient photocells that respond instantly to changing light levels."
A nonmetallic chemical element (symbol Se) with an atomic number of 34, used mainly in glassmaking and pigments and as a semiconductor.
"The engineer noted that selenium's unique properties make it essential for both the vibrant colors in stained glass and its role as a semiconductor in modern electronics."
The name selenium comes from the French word coined in 1818 by Swedish chemist Jöns Jacob Berzelius. He derived it from the Ancient Greek word for "moon" because he initially confused the new element with tellurium.