halogen

halo·gen

noun \ˈhal-ə-jən\

Definition of HALOGEN

: any of the five elements fluorine, chlorine, bromine, iodine, and astatine that form part of group VII A of the periodic table and exist in the free state normally as diatomic molecules

—ha·log·e·nous \ha-ˈläj-ə-nəs\ adjective