iodine

noun, often attributive io·dine \ ˈī-ə-ˌdīn , -dᵊn , -ˌdēn \

|Updated on: 8 Jul 2018

Definition of iodine

1 : a nonmetallic halogen element obtained usually as heavy shining blackish-gray crystals and used especially in medicine, photography, and analysis — see Chemical Elements Table

2 : a tincture of iodine used especially as a topical antiseptic

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See iodine defined for kids

Recent Examples of iodine from the Web

Russia's Energia Rocket and Space Corporation (aka S.P. Korolev Rocket and Space Corporation Energia) is developing a new electric propulsion rocket engine operating on iodine, TASS reports.

— eric berger, Ars Technica, "Rocket Report: Small sat market surging, Proton dying, Falcon Heavy certified," 29 June 2018
Also, American food is highly fortified -- with vitamin D in milk, iodine in salt, B vitamins in flour, even calcium in some brands of orange juice.

— liz szabo, CNN, "Enthusiasm over vitamins often outpaces evidence, experts say," 13 Apr. 2018
Fish is high in many important nutrients, including high quality protein, iodine and various vitamins and minerals.

— orthocincy, Cincinnati.com, "Benefits of eating fish," 19 June 2018
State health officials recommend disinfecting the bite site with rubbing alcohol, an iodine scrub, or soap and water.

— don behm, Milwaukee Journal Sentinel, "Heading outdoors? Here's how to protect yourself from a full bloom of mosquitoes and ticks in Wisconsin," 30 May 2018
Alternatively, heavy WIMPs will interact almost exclusively with iodine atoms at low energies and very little with sodium.

— natalie wolchover, WIRED, "Trouble Detected in Infamous Dark Matter Signal," 18 Apr. 2018
The ingestion of red ochre, suggests Duarte, combined with consumption of seafood, boosted early humans’ supply of docosahexaenoic acid (DHA) and iodine as well as, potentially, iron and other nutrients essential for brain development.

— gemma tarlach, Discover Magazine, "Pigment of Our Imagination," 23 Mar. 2018
Skin is then painted a muddy copper with Betadine iodine solution until a patient no longer looks human, more like a piece of meat.

— Longreads, "Somewhere Under My Left Ribs: A Nurse’s Story," 31 May 2018
The star received radioactive iodine therapy for the disease, which had spread to his lymph nodes.

— taysha murtaugh, Country Living, "Inside Tarek El Moussa's Scary Cancer Battle—and One of His Healthiest Flip or Flop Seasons Yet," 29 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'iodine.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Did You Know?

Iodine is a nonmetallic chemical element and the heaviest nonradioactive halogen. It is a very nearly black crystalline solid that can turn to a deep violet, irritating vapor. In nature it is never found uncombined, and occurs mostly in brines and seaweeds. Dietary iodine is essential for thyroid gland function, so table salt usually has potassium iodide added to prevent iodine deficiency. Elemental iodine is used in medicine, in synthesizing some organic chemicals, in manufacturing dyes, in analytical chemistry, and in photography. The radioactive isotope I-131, with an eight-day half-life, is very useful in medicine and other applications.

Origin and Etymology of iodine

French iode "iodine" (borrowed from Greek ioeidḗs "violet-colored," from íon "the color violet"—going back to *wion, akin to the source of Latin viola "the violet flower"— + -o-eidēs ²-oid) + ²-ine (after chlorine, fluorine) — more at violet

Note: The French word iode was apparently introduced by the chemists Bernard Courtois (1777-1838) and Joseph Louis Gay-Lussac (1778-1850); cf. B. Courtois, "Découverte d'une substance nouvelle dans le Vareck," Annales de chimie, tome 88 (1813), p. 305: "La substance nouvelle, que depuis on a nommé iode à cause de la belle couleur violette de sa vapeur, a bien tout l'aspect d'un métal." ("The new substance, which since has been named iode because of the beautiful violet color of its vapor, has all the appearance of a metal.") Note that a borrowing from Greek ioeidḗs should properly have yielded ioïde in French rather than iode; the direct source of the latter may have been iṓdēs "rust-colored," a derivative of íos "rust, verdigris," taken erroneously to be a derivative of íon "the color violet."

NEW! Time Traveler

First Known Use: 1814

in the meaning defined at sense 1

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IODINE Defined for English Language Learners

iodine

noun

Definition of iodine for English Language Learners

: a chemical element that is used especially in medicine and photography

IODINE Defined for Kids

iodine

noun io·dine \ ˈī-ə-ˌdīn , -dᵊn \

Definition of iodine for Students

1 : a chemical element found in seawater and seaweeds and used especially in medicine and photography

2 : a solution of iodine in alcohol used to kill germs

Medical Dictionary

iodine

noun, often attributive io·dine \ ˈī-ə-ˌdīn , -əd-ᵊn , -ə-ˌdēn \

medical Definition of iodine

1 : a nonmetallic halogen element obtained usually as heavy shining blackish gray crystals and used especially in medicine (as in antisepsis and in the treatment of goiter and cretinism) and in photography and chemical analysis —symbol I — see Chemical Elements Table

2 : a tincture of iodine used especially as a topical antiseptic