Iodine

How to spell iodine

6 letters · 3 syllables

How to pronounce iodine

Say the part in capitals loudest.

What does iodine mean?

1. nounA non-metallic chemical element, used as an antiseptic and as a dietary nutrient, that gives off a violet vapour when heated.

Iodine in a sentence

• The nurse dabbed iodine on the cut to prevent infection.

• Table salt is often fortified with iodine to support thyroid health.

Where does iodine come from?

Language of origin: Greek

Iodine takes its name from the Greek word iodes, meaning 'violet-coloured', which itself was built from ion 'violet' and eidos 'form' or 'appearance'. The element was first isolated in 1811 by the French chemist Bernard Courtois, who noticed a striking purple vapour rising when he treated seaweed ash with sulphuric acid. A few years later the chemist Joseph Louis Gay-Lussac proposed the name in French as iode, directly because of that violet gas, and Humphry Davy in England adapted it into iodine using the -ine ending that English commonly attaches to chemical substances. The spelling trap lives in that opening: the unstressed 'io' that begins the word is easy to garble, and the silent finish of -ine catches writers who hear a long vowel. Knowing the violet vapour story fixes both the 'io' from ion and the chemical -ine in mind.

How the word is built

• iod- (from Greek iodes: violet-coloured)
• -ine (suffix marking a chemical element or substance)