Definitions of contradictory:

• noun:   two propositions are contradictories if both cannot be true (or both cannot be false) at the same time
• adjective:   of words or propositions so related that both cannot be true and both cannot be false

  Example: "`perfect' and `imperfect' are contradictory terms"

• adjective:   unable to be both true at the same time
• adjective:   that confounds or contradicts or confuses
• adjective:   in disagreement

  Example: "Contradictory attributes of unjust justice and loving vindictiveness- John Morley"