GNU Collaborative International Dictionary of English

Found one definition

1.       
    Cossic (k?sˈs?k), Cossical (-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).
   
   [1913 Webster]