Merriam-Webster Collegiate Dictionary - contradiction

 noun  Date: 14th century  1. act or an instance of contradicting  2.  a. a proposition, statement, or phrase that asserts or implies both the truth and falsity of something  b. a statement or phrase whose parts contradict each other a round square is a ~ in terms  3.  a. logical incongruity  b. a situation in which inherent factors, actions, or propositions are inconsistent or contrary to one another