Source : Webster's Revised Unabridged Dictionary (1913)

Cossic \Cos"sic\ (k?s"s?k), Cossical \Cos"sic*al\ (-s?-kal), a.
   [It. cossico. See 2d {Coss}.]
   Of or relating to algebra; as, cossic numbers, or the cossic
   art. [Obs.] ``Art of numbers cossical.'' --Digges (1579).