Contraposition
Pronunciation : Con"tra*po*si"tion
Part of Speech : n.
Etymology : [Pref. contra- + position: cf. f. conterposition.]
Definition : 1. A placing over against; opposite position. [Obs.] F. Potter.
2. (Logic)
Defn: A so-called immediate inference which consists in denying the original subject of the contradictory predicate; e.g.: Every S is P; therefore, no Not-P is S.
Source : Webster's Unabridged Dictionary, 1913