adjective
Definition: Relating to or containing a group of elements in the periodic table that includes fluorine, chlorine, bromine, iodine, and astatine, known for their reactivity and ability to form salts with metals.
Example: The halogen compounds are often used in disinfectants and light bulbs.
noun
Definition: A group of five nonmetal elements that include fluorine, chlorine, bromine, iodine, and astatine, known for their chemical reactivity.
Example: Fluorine is the most reactive halogen and is used in many chemical applications.