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) • Syn: selenium, atomic number 34 • Hypernyms: chemical element, element, antioxidant • Substance Holonyms: pyrite, iron pyrite, fool's gold
