The Collaborative International Dictionary of English v.0.48:

Hyperchloric \Hy`per*chlo"ric\, a. (Chem.)
   See Perchloric.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Perchloric \Per*chlo"ric\, a. [Pref. per- + chloric.] (Chem.)
   Pertaining to, or designating, the highest oxygen acid
   (HClO4), of chlorine; -- called also hyperchloric.
   [1913 Webster]