iodine Meaning, Definition & Usage

  1. noun a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks)
    iodin; I; atomic number 53.
  2. noun a tincture consisting of a solution of iodine in ethyl alcohol; applied topically to wounds as an antiseptic
    tincture of iodine.

WordNet

I"o*dine noun
Etymology
Gr. violetlike; a violet + form: cf. F. iode, iodine. The name was given from the violet color of its vapor. See Violet, Idyl.
Definitions
  1. (Chem.) A nonmetallic element, of the halogen group, occurring always in combination, as in the iodides. When isolated it is in the form of dark gray metallic scales, resembling plumbago, soft but brittle, and emitting a chlorinelike odor. Symbol I. Atomic weight 126.5. If heated, iodine volatilizes in beautiful violet vapors. ✍ Iodine was formerly obtained from the ashes of seaweed (kelp or varec), but is now also extracted from certain natural brines. In the free state, iodine, even in very minute quantities, colors starch blue. Iodine and its compounds are largely used in medicine (as in liniments, antisyphilitics, etc.), in photography, in the preparation of aniline dyes, and as an indicator in titration.

Webster 1913