noun
also io·din ˈīəˌdīn also -_də̇n or -d ə n or -ˌdēn
( -s )
Etymology: French iode iodine (from Greek ioeidēs purple, violet colored, from ion violet + -oeidēs -oid) + English -ine (II) or -in — more at violet
: a nonmetallic univalent and polyvalent element belonging to the halogens that is obtained usually as heavy shining blackish gray crystals subliming to a violet-colored irritating vapor, that occurs naturally only in combination in small quantities especially in seawater, rocks, soils, and underground brines and in marine plants and animals, that is essential for the normal functioning of the thyroid gland of all vertebrates, that is usually extracted from the ashes of seaweeds, from Chile saltpeter, or from oil-well brines, and that is used chiefly in medicine (as in antisepsis and in the treatment of cretinism and goiter), photography, and analysis — symbol I ; see element table