antithetical

opposite, contradictory, contrary, antithetical mean being so far apart as to be or seem irreconcilable. opposite applies to things in sharp contrast or in conflict <opposite views on foreign aid>. contradictory applies to two things that completely negate each other so that if one is true or valid the other must be untrue or invalid <made contradictory predictions about whether the market would rise or fall>. contrary implies extreme divergence or diametrical opposition <contrary assessments of the war situation>. antithetical stresses clear and unequivocal diametrical opposition <a law that is antithetical to the very idea of democracy>.