Definition of: iodine

(ī′ə·dīn, -din, -dēn) noun
A bluish–black crystalline element (symbol I) of the halogen group, having a metallic luster and yielding, when heated, corrosive fumes of a rich violet color. It is valuable for its powerful antiseptic properties, and is applied externally as a counterirritant. It is also extensively used in photography and organic synthesis. See ELEMENT. Also i·o·din (ī′ə·din). [<F iode <Gk. iōdēs violetlike (<ion a violet + eidos form) + -INE² (as in chlorine); from its violet–colored vapor]