mutatis mutandis UK /m(j)uːˌtɑːtɪs muːˈtandɪs/US /m(j)uˌtɑtəs m(j)uˈtɑndəs/ adverb1 •With the necessary changes being made; with the necessary modifications; with such changes as are necessary to ensure congruence.And like billes, mutatis mutandis, were put In ayenst Gloucestre & Worcestre — 1525