heterogeneous

Heterogeneous describes something composed of different parts, elements, or phases. The term comes from the Greek heteros 'other' and genēs 'born' or 'kind.' In general usage, a heterogeneous system is not uniform in composition or properties. It is often contrasted with homogeneous, meaning uniform in composition.

A heterogeneous mixture contains distinct substances that can be separated physically, such as salad, granite, or oil in water. In materials science, heterogeneity often refers to a material with multiple phases or constituents, where properties vary with location and interfaces between phases influence strength, transport, and reactivity.

In chemistry, heterogeneous catalysis occurs at interfaces between phases, for example a solid catalyst with a gaseous or liquid reactant. This contrasts with homogeneous catalysis, where all species are in the same phase. In computing, heterogeneous systems combine different processors or devices, and in data science, heterogeneous data sources require integration and harmonization.

In statistics and epidemiology, heterogeneity describes variation across observations, studies, or populations; models may account for it with random effects or subgroup analyses. In biology and ecology, heterogeneity underlies tissue structure and population diversity, with spatial or genetic variation shaping function and dynamics.