13 letters · 21 points in Scrabble
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
adjective that confounds or contradicts or confuses
originBorrowed from Late Latin contradictorius, from Latin contradico. Equivalent to contradict + -ory.
Etymology from Wiktionary, CC BY-SA 3.0