Main Entry: ¹con·tra·dic·to·ry

Pronunciation: \ˌkän-trə-ˈdik-t(ə-)rē\

Function: noun

Inflected Form(s): plural con·tra·dic·to·ries

Date: 14th century

: a proposition so related to another that if either of the two is true the other is false and if either is false the other must be true