Con`tra*dict"o*ry (?), a. [LL. contradictorius: cf. F. contradictoire.] 1. Affirming the contrary; implying a denial of what has been asserted; also, mutually contradicting; inconsistent. "Contradictory assertions." South.

2. Opposing or opposed; repugnant.

Schemes . . . contradictory to common sense.
Addisn.

Con`tra*dict"o*ry, n.; pl. Contradictories (&?;). 1. A proposition or thing which denies or opposes another; contrariety.

It is common with princes to will contradictories.
Bacon.

2. pl. (Logic) propositions with the same terms, but opposed to each other both in quality and quantity.

• that contradicts something, such as an argument
  
• that is itself a contradiction
  
• that is diametrically opposed to something
  
• mutually exclusive
  
• (logic) any of a pair of propositions, that cannot both be true or both be false