I have heard the term "orthogonal * validation" used recently. It was used in the context of experimental platform testing. What does this mean? I cannot find anything on it in literature or Wikipedia.
Basically, it would seem that people use orthogonal as a synonym for independent. So, for orthogonal validation read independent validation The validity of equating orthogonality with independence is discussed here such that "if X and Y are independent then they are Orthogonal" but "the converse is not true".