The anion name for HI is iodide, and the acid name for HI is hydroiodic acid.
HI is a binary acid, which means it consists of hydrogen and a nonmetal, in this case, iodine. When HI is in solution, it dissociates into hydrogen ions (H+) and iodide ions (I–). The nomenclature for naming acids depends on the presence of certain elements; for binary acids like HI, the naming convention uses the prefix ‘hydro-‘ along with the root of the nonmetal name, followed by the suffix ‘-ic’. Therefore, iodine becomes hydroiodic acid when hydrogen bonds with it. The anion produced in this process, the iodide ion, is simply named by taking the root of the iodine name and adding ‘-ide’. Hence, we have iodide as the anion associated with hydroiodic acid.