re·pu·di·ate /ri-'pyü-dē-ˌāt/ vt -at·ed, -at·ing: to disavow or reject an obligation (as a debt) or duty (as performance under a contract); specif: to indicate an inability or unwillingness to perform as promised under (a contract)
re·pu·di·a·tor /-ˌā-tər/ n
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.