[con.tra.dic.to.ry] n, pl -ries (14c): a proposition so related to another that if either of the two is true the other is false and if either is false the other must be true
[2]contradictory adj (1534): involving, causing, or constituting a contradiction syn see opposite -- con.tra.dic.to.ri.ly adv -- con.tra.dic.to.ri.ness n