[n] two propositions are contradictories if both cannot be true (or both cannot be false) at the same time
[adj] unable to be both true at the same time
[adj] in disagreement; "the figures are at odds with our findings"; "contradictory attributes of unjust justice and loving vindictiveness"- John Morley
[adj] that confounds or contradicts or confuses
[adj] of words so related that both cannot be true and both cannot be false; "`perfect' and `imperfect' are contradictory terms"