Complementary

Complementary describes things that complete, enhance, or go well with each other. The term is used across disciplines to denote a relationship in which two elements yield a whole that neither could achieve alone. It can refer to something that completes another thing, or to a pair whose qualities contrast and balance.

In mathematics and geometry, complementary angles are two angles that add up to 90 degrees. In probability, two events are complementary if the occurrence of one excludes the other and their probabilities sum to one; the complement of an event A is not A.

In science and everyday use, complementary colors are colors opposite each other on the color wheel and create high contrast when placed together. When light is mixed, complementary colors can produce white or neutral tones.

In economics, complementary goods are products that are often consumed together, so demand for one increases with the other (for example printers and ink cartridges).

In biology, complementary base pairing describes how DNA strands align: adenine pairs with thymine, and cytosine pairs with guanine, enabling accurate replication.

In medicine, complementary approaches refer to practices used together with conventional medical treatments, such as complementary therapies in cancer care.

In linguistics, complementarity describes a distributional relationship where two linguistic elements occur in non-overlapping environments, effectively completing each other’s use within a system.