iodine

noun

io·​dine ˈī-ə-ˌdīn  -dᵊn  -ˌdēn 

often attributive

1

: a nonmetallic halogen element that is an essential nutrient in the human diet and is used especially in medicine, photography, and analytical chemistry see Chemical Elements Table

2

: a tincture of iodine used especially as a topical antiseptic

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.

Examples of iodine in a Sentence

Recent Examples on the Web

Now, the Liverpool researchers have addressed the ion-transport issue with a new solid electrolyte made out of lithium, silicon, sulfur, and iodine that takes the shape of a three-dimensional crystal structure. —IEEE Spectrum, 15 Feb. 2024

Cress Rich in vitamin C and minerals such as iron, calcium, potassium, phosphorus, and iodine, watercress is part of the cruciferous family, like cauliflower. —Alessandra Signorelli, Vogue, 27 June 2023

In the case of radiation leakage, radioactive iodine is one of the materials that may be released into the environment and can be absorbed and stored in the thyroid, which relies on iodine for hormone synthesis. —Kylie Martin, Detroit Free Press, 28 Mar. 2024

Even mild iodine deficiency during pregnancy can lead to subtle intellectual deficits, although many children improve with iodine supplementation. —Mary Shomon, Verywell Health, 17 Sep. 2023

From iodine to iron, calcium to magnesium, this little capsule contains a wealth of nutrients that can help boost your immune system, improve digestion, and support thyroid function. —Amber Smith, Discover Magazine, 5 July 2023

If iodine deficiency isn't the cause of hypothyroidism, then iodine supplements won't be helpful. —Mary Shomon, Verywell Health, 17 Sep. 2023

While giving a tour of the farm hours before caroling, Mr. Vinson described the precautions taken at Churchtown Dairy, including regular testing and treating the cows’ udders with an iodine solution. —Arielle Gordon Alexandra Genova, New York Times, 19 Dec. 2023

And, since most of us get enough iodine already from eating fish, dairy, and iodized table salt, this is a worthwhile concern. —Vogue, 8 Dec. 2023

Word History

Etymology

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 -oid entry 2) + -ine entry 2 (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."

First Known Use

1814, in the meaning defined at sense 1

Phrases Containing iodine

• quartz-iodine lamp

Kids Definition

iodine

noun

io·​dine ˈī-ə-ˌdīn 

-əd-ᵊn,

-ə-ˌdēn

variants also iodin

ˈī-əd-ᵊn

1

: a nonmetallic element that is obtained usually as heavy shining blackish gray crystals and is used especially in medicine and photography see element

2

: a solution of iodine in alcohol used to kill germs

Medical Definition

iodine

noun

io·​dine ˈī-ə-ˌdīn  -əd-ᵊn  -ə-ˌdēn 

often attributive

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