COSS is a 4 letter word that starts with C.

1. \Coss\ (k[o^]s), n. [Cf. Pers. k[=o]s a road measure of
   about two miles; or Skr. kr[=o][,c]a.]
   A Hindoo measure of distance, varying from one and a half to
   two English miles. --Whitworth.
   
   

2. \Coss\, n. [It. cosa.]
   A thing (only in phrase below).
   
   {Rule of Coss}, an old name for Algebra. [It. regola di cosa
      rule of thing, the unknown quantity being called the cosa,
      or the thing.]
   
   

common object services specification in corba.