complementary

Complementary means two or more things working together to enhance each other. For example, in a complementary metal oxide semiconductor (CMOS), two transistors work in harmony to save electricity (see CMOS).

Complementary is often confused with complimentary because they sound the same and are similarly spelled. However, complimentary with an "i" means to praise someone or some thing, and complementary with an "e" means a counterpart.