What does iodine mean?
Iodine is a chemical element and halogen whose symbol is I. In its pure form it is a lustrous grey-black solid, but its compounds can produce a characteristic violet vapour, which inspired the element’s name. Iodine occurs naturally in seawater, rocks, and the human body, where it is needed in small quantities for the thyroid gland to produce hormones that regulate metabolism and growth. Because many diets contain too little iodine, it is sometimes added to table salt or supplied as supplements such as iodine tablets. In medicine, iodine or iodine tincture is used as an antiseptic for minor cuts, grazes, and other skin injuries. The element is also important in industry and in nuclear medicine, where radioactive iodine is used in the diagnosis and treatment of certain thyroid conditions. Its history links chemistry with natural history: it was first recognized as a distinct substance through the study of seaweed ash and the behaviour of its coloured vapour.
nounIodine is a chemical element and halogen represented by the symbol I; in common use, the term also refers to a brownish solution or compound used as an antiseptic. It occurs naturally in seawater, rocks, and living organisms, and is essential in small amounts for thyroid function.
- The chemical element iodine, a halogen occurring mainly in compounds and present in seawater and rocks.
- An antiseptic preparation, often a brown solution of iodine in alcohol, applied to minor wounds or used to disinfect surfaces.
"The doctor applied iodine to the cut before covering it with a sterile bandage."
"Iodine is added to table salt in some regions to help prevent iodine deficiency."
"The nurse cleaned the site with iodine before giving the injection."
The plural is rare in ordinary usage because iodine is normally treated as an uncountable substance or a singular chemical element.
"The inventory distinguishes iodines supplied for different laboratory preparations."
Iodine was named for the violet colour of its vapour, and the same element helps the human body regulate metabolism through the thyroid gland.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does iodine come from?
The word iodine comes from the Greek noun iōdē, meaning “violet,” referring to the colour of iodine vapour, combined with the chemical suffix -ine. The element was isolated in the early 19th century through work involving seaweed ash, and its name was soon adopted in English. The same Greek root appears in related chemical terms such as iodate, iodide, and iodize, all of which refer to iodine or its compounds.
Related word forms
How iodine is actually used
In medical and laboratory contexts, iodine can refer to the elemental substance, an iodine-containing antiseptic, or a dietary supplement. In everyday British English, the antiseptic form is often called iodine; in American English, iodine is also commonly used for the element and for preparations such as iodine tablets.
Easily confused with iodine
Iodine is the chemical element, while an iodide is a compound or ion containing iodine bonded with another element, commonly sodium or potassium.