The term ethnotaxonomy refers either to that subdiscipline within ethnology which studies the taxonomic systems defined and used by individual ethnic groups, or to the operative individual taxonomy itself, which is the object of the ethnologist's immediate study.
For example, in many West African languages, the perceptual world of color is classified into the principal categories "Red," "White," and "Black" (finer gradations being secondary). The range of wavelengths that an English-speaker calls blue would be a subcategory of "Black."
The set of categories of familial relationships evinced by the ethnic group's kinship system is another ethnotaxonomy. An example of this might be the Hawaiian kinship system, where all members of a generation of the same sex are referred to by a single term. Both the relationships termed mother and aunt in English fall into the same taxon "Mother-Aunt". This does not mean that the users of this taxonomy are confused about the concept "Birth-Mother," only that it is a subcategory.
Conversely, an ethnotaxonomy such as the Sudanese kinship system or that used in ancient Rome, where no two relationships have the same denotation, may show much more granularity than the English system. Thus the relationship called aunt in English is not fundamental in Latin, but either amita "Father's Sister" or matertera "Mother's Sister" must be chosen. Latin and Sudanese are called a "descriptive systems," and Hawaiian is called a "classificatory" system, but this terminology is English-centered (see Lewis H. Morgan), the difference being one of degree, rather than kind.
Categories of plants, "Useful" and "Harmful," etc., are yet another well-known example. Indeed, in recent years there has been a vogue usage of the term ethnotaxonomy limiting it to ethnobotany and ethnopharmacology, because of the "rediscovery" of the medicinal and commercial value of plants disclosed by examining the botanical ethnotaxonomies of lesser-known cultures.