The Collaborative International Dictionary of English v.0.48:

Iodide \I"o*dide\, n. (Chem.)
   A binary compound of iodine, or one which may be regarded as
   binary, in which iodine has a valence of -1; as, potassium
   iodide.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

iodide
    n 1: a salt or ester of hydriodic acid