iodine

American  

[ahy-uh-dahyn, -din, ahy-uh-deen] / ˈaɪ əˌdaɪn, -dɪn, ˈaɪ əˌdin /

Sometimes iodin

noun

Chemistry.

iodines plural

1. a nonmetallic halogen element occurring at ordinary temperatures as a grayish-black crystalline solid that sublimes to a dense violet vapor when heated: used in medicine as an antiseptic. I; 126.904; 53; (solid) 4.93 at 20°C.

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iodine British  

/ ˈaɪəˌdiːn /

noun

1. a bluish-black element of the halogen group that sublimates into a violet irritating gas. Its compounds are used in medicine and photography and in dyes. The radioisotope iodine-131 ( radioiodine ), with a half-life of 8 days, is used in the diagnosis and treatment of thyroid disease. Symbol: I; atomic no: 53; atomic wt: 126.90447; valency: 1, 3, 5, or 7; relative density: 4.93; melting pt: 113.5°C; boiling pt: 184.35°C

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iodine Scientific  

/ ī′ə-dīn′ /

1. A shiny, grayish-black element of the halogen group. It is corrosive and poisonous and occurs in very small amounts in nature except for seaweed, in which it is abundant. Iodine compounds are used in medicine, antiseptics, and dyes. Atomic number 53; atomic weight 126.9045; melting point 113.5°C; boiling point 184.35°C; specific gravity (solid, at 20°C) 4.93; valence 1, 3, 5, 7.

2. See Periodic Table

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Other Word Forms

Noun Inflected Forms

• iodines
  plural

Etymology

Origin of iodine

First recorded in 1814; from French iode + -ine ² ( def. 2 ); introduced by H. Davy. Ultimately from Greek īṓdēs, originally “rust-colored”, but by folk etymology taken as í(on) “violet” + -ōdēs noun suffix; see -ode ¹ ( def. )

Compare meaning

How does iodine compare to similar and commonly confused words? Explore the most common comparisons:

• iodide vs. iodine
• Betadine vs. iodine
• povidone-iodine vs. iodine

Example Sentences

See Examples For:

iodine iodines

A short walk along an irrigation canal leads to a weathered observation deck rising two stories above a patchwork of saturated flats where saltgrass, iodine bush and cattail take root.

From Los Angeles Times ● Apr. 7, 2026

They then measured the actual amounts of choline and iodine in their lab versus what was on the label and also checked for arsenic, lead and cadmium.

From Science Daily ● Nov. 21, 2024

Their checklist also includes iodine tablets, as well as easy-to-cook food, pet food and a backup power supply.

From BBC ● Nov. 17, 2024

Due to the high iodine content in many seaweed species, seaweed consumption could exacerbate thyroid conditions or interfere with thyroid medications.

From Salon ● Aug. 5, 2024

The doctor listened with his stethoscope and then painted a circle on his chest with a piece of cotton dipped in iodine.

From "One Hundred Years of Solitude" by Gabriel Garcia Marquez

In the colloid, peroxidase enzymes link the iodine to the tyrosine amino acids in thyroglobulin to produce two intermediaries: a tyrosine attached to one iodine and a tyrosine attached to two iodines.

From Textbooks ● Jun. 19, 2013