halogen

noun

Etymology: From Ancient Greek ἅλς (háls, “salt" or "sea”) + γεν- (gen-), "to produce" (coined by Berzelius in 1842). By surface analysis, halo- (“salt”) + -gen (“forming”).

1. Any element of group 17, i.e. fluorine, chlorine, bromine, iodine, astatine and tennessine.

   “Plant 12 also stored super sacks of bromochloro-5,5-dimethylimidazolidine-2,4-dione (BCDMH), which is a granular solid oxidizer with a halogen odor that, in addition to chlorine gas and hydrogen chloride, can also release bromine gas and hydrogen bromide upon decomposition.”

2. A light fixture in which the filament is surrounded by an atmosphere of a halogen gas.