Ethnolinguistics is a field of linguistic anthropology which studies the language of a particular ethnic group.
Ethnolinguistics is frequently associated with minority linguistic groups within a larger population, such as the Native American languages or the languages of immigrants. In these cases, ethnolinguistics studies the use of a minority language within the context of the majority population, and it also studies the perception of the language by the majority population.
More generally, ethnolinguistics studies the relationship between language and culture, and the way different ethnic groups perceive the world. A well-known (but controversial) ethnolinguistic subject is the Sapir-Whorf Hypothesis, which states that perception is limited by what can be described in one's own language.
Ethnolinguists study the way perception and conceptualization influences language, and show how this is linked to different cultures and societies. An example is the way spatial orientation is expressed in various cultures (Bernd Heine 1997, Yi-Fu Tuan 1974). In many societies, words for the cardinal directions East and West are derived from terms for sunrise/sunset. The nomenclature for cardinal directions of Eskimo speakers of Greenland, however, is based on geographical landmarks such as the river system and one's position on the coast. Similarly, the Yurok lack the idea of cardinal directions; they orient themselves with respect to their principal geographic feature, the Klamath River.