*hydriodic*

a. [ Hydr- + iodic: cf. F. hydriodique. ] (Chem.) Pertaining to, or derived from, hydrogen and iodine; -- said of an acid (HI) produced by the combination of these elements. [ 1913 Webster ]

Hydriodic acid (Chem.), a pungent, colorless gas, HI, usually prepared as a solution in water. It is strong reducing agent. Called also hydrogen iodide. [ 1913 Webster ]