Homogeneity & heterogeneity are notion often used in a sciences as alive as statistics relating to a uniformity of a substance or organism. A material or image that is homogeneous is uniform in composition or unit of reference i.e. color, shape, size, weight, height, distribution, texture, language, income, disease, temperature, radioactivity, architectural design, etc.; one that is heterogeneous is distinctly nonuniform in at least one of these qualities.
The words homogeneous and heterogeneous come from Medieval Latin homogeneus and heterogeneus, from Ancient Greek ὁμογενής homogenēs and ἑτερογενής heterogenēs, from ὁμός homos, “same” and ἕτερος heteros, “other, another, different” respectively, followed by γένος genos, “kind”; -ous is an adjectival suffix.
Alternate spellings omitting the last -e- and the associated pronunciations are common, but mistaken: homogenous is strictly a biological/pathological term which has largely been replaced by homologous. But ownership of homogenous to intend homogeneous has seen a rise since 2000 sufficient enough for it to now be considered an "established variant". Similarly, heterogenous is a spelling traditionally reserved to biology and pathology, referring to the property of an thing in the body having its origin outside the body.