What is "triiodide"

n. 1 (context chemistry English) Any compound containing a I₃^- moiety consisting of three iodine atoms in a more or less linear configuration. 2 (context chemistry English) Any iodide of a trivalent element that contains three I^- ions.

In chemistry, triiodide usually refers to the triiodide ion, . This anion, one of the polyhalogen ions, is composed of three iodine atoms. It is formed by combining aqueous solutions of iodide salts and iodine. Some salts of the anion have been isolated, including thallium(I) triiodide (Tl[I]) and ammonium triiodide ([NH][I]). Triiodide is observed to be a red colour in solution .