i·o·dine (īə-dīn′, -dĭn, -dēn′)
1. Symbol I A lustrous, purple-black, corrosive, poisonous halogen occurring as a diatomic molecule, I2, that easily sublimes to give a purple gas and is a trace element essential for proper thyroid function. Radioactive isotopes, especially I-131, are used as medical tracers and in thyroid disease diagnosis and therapy. Iodine compounds are used as germicides, antiseptics, and dyes. Atomic number 53; atomic weight 126.9045; melting point 113.7°C; boiling point 184.4°C; density of gas 11.27 grams per liter; specific gravity (solid, at 20°C) 4.93; valence 1, 3, 5, 7. See Periodic Table.
2. An antiseptic preparation containing iodine in solution, used to treat wounds.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.