In linguistics, complementary distribution, as distinct from contrastive distribution and free variation, is the relationship between two different elements of the same kind in which one element is found in one set of environments and the other element is found in a non-intersecting (complementary) set of environments. In linguistics, complementary distribution, as distinct from contrastive distribution and free variation, is the relationship between two different elements of the same kind in which one element is found in one set of environments and the other element is found in a non-intersecting (complementary) set of environments.