Noun
(linguistics) a distribution of related speech sounds or forms in such a way that they only appear in different contexts
Source: WordNetStep 3, discover which sets are in complementary distribution During the late 18th to late 19th century, two major developments improved the method's effectiveness. Source: Internet
The two forms are mostly in complementary distribution – certain contexts call for one, and certain contexts for the other; they are not normally interchangeable, except in occasional instances like after the verb help, where either can be used. Source: Internet
This is not straightforward because the maximum difference between two joint cumulative distribution functions is not generally the same as the maximum difference of any of the complementary distribution functions. Source: Internet