Iodothyronines

Part of speech: noun

Definitions

1. Compounds derived from thyroid hormones that contain iodine atoms as part of their molecular structure
2. Organic molecules based on thyroid hormones characterized by the presence of iodine within their chemical composition
3. Iodine-containing derivatives of thyroid hormones important for regulating metabolism and bodily functions

Etymology: Iodothyronines are a family of compounds named by building up from their chemistry: they are thyronines, a core structure built from two linked rings, carrying iodine atoms. The name is a compound of "iodo-", the chemical prefix for iodine, and "thyronine," the name for the parent structure, which takes its stem from the thyroid gland, where these molecules were first found. The whole word is therefore a plain technical coinage from the 20th-century chemistry of hormones, not a survival from older English. The "iodo-" part traces back to "iodine" itself, which was named in 1813 by the chemist Joseph Louis Gay-Lussac from the Greek "ioeidēs," meaning "violet-coloured," because the vapour of the element shows a deep violet hue when heated. That Greek adjective is built from "ion," the violet flower, and "eidos," meaning form or appearance, with the suffix "-ēs" that turns it into an adjective. So the chemical name for a substance that glows violet as a gas also sits behind the iodine in these hormones.