W: (adj) contradictory [Related to: contradict] (of words or propositions so related that both cannot be true and both cannot be false) "`perfect' and `imperfect' are contradictory terms"
W: (n) contradiction [Related to: contradict] (the speech act of contradicting someone) "he spoke as if he thought his claims were immune to contradiction"
W: (adj) negative [Related to: negate] (expressing or consisting of a negation or refusal or denial)
W: (n) negation [Related to: negate] (a negative statement; a statement that is a refusal or denial of some other statement)
S: (v) neutralize, neutralise, nullify, negate (make ineffective by counterbalancing the effect of) "Her optimism neutralizes his gloom"; "This action will negate the effect of my efforts"