a conditional statement derived from another by negating and interchanging antecedent and consequent
b.
a categorial proposition obtained from another, esp validly, by any of a number of operations including negation, transferring the terms, changing their quality, and also possibly weakening from universal to particular
contrapositive in American English
(ˈkɑntrəˈpɑzəˌtɪv)
noun
Logic
a proposition obtained by negating and transposing the terms of a given proposition
the contrapositive of “All A is B” is “All not-B is not-A”