Any of a group of five chemically related nonmetallic elements including fluorine, chlorine, bromine, iodine, and astatine.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "halogen" in a sentence
"All the halogen is obtained with the washing liquid in the form of sodium halide, all the sulphur in the form of sulphuric acid."
"There is a group of closely allied elements to which the name halogen"
"Tungsten halogen bulbs are actually another type of incandescent bulb; they are often simply called halogen bulbs."