Wiktionary
non-repudiation
n. (alternative spelling of nonrepudiation English)
Wikipedia
Non-repudiation
Non-repudiation refers to a state of affairs where the author of a statement will not be able to successfully challenge the authorship of the statement or validity of an associated contract. The term is often seen in a legal setting wherein the authenticity of a signature is being challenged. In such an instance, the authenticity is being "repudiated".