Source : Webster's Revised Unabridged Dictionary (1913)

Octonary \Oc`to*na*ry\, a. [L. octonarius, fr. octoni eight
   each, fr. octo eight.]
   Of or pertaining to the number eight. --Dr. H. More.

Source : WordNet®

octonary
     n : the cardinal number that is the sum of seven and one [syn: {eight},
          {8}, {VIII}, {eighter}, {eighter from Decatur}, {octad},
          {ogdoad}, {octet}]