noun
complementary distribution
Technical term in linguistics describing two or more elements that never occur in the same environment.
日本語の「は」と「が」は相補分布の関係にあると言われることがある。
It is sometimes said that Japanese 'wa' and 'ga' are in complementary distribution.
音韻論では、相補分布を示す音は同一音素の異音と見なされる。
In phonology, sounds that show complementary distribution are considered allophones of the same phoneme.