Aztec-Tanoan hypothesis, a proposed remote linguistic affiliation between the Uto-Aztecan and Kiowa-Tanoan language families of American Indian languages. The hypothesis was advanced in 1929 by American linguist Edward Sapir, who called it Aztec-Tanoan. (Linguists Benjamin L. Whorf and George L. Trager in 1937 called it Azteco-Tanoan, but Sapir’s name for the grouping has predominated.) Uto-Aztecan is a relatively large language family whose member languages were spoken from Oregon to Nicaragua, and several are still spoken in the U.S. in the Great Basin, California, and Arizona; in Mexico; and in El Salvador. The four Kiowa-Tanoan languages are spoken in New Mexico, Arizona, and Oklahoma and formerly were also spoken in Texas.

Most of the evidence offered in support of the Aztec-Tanoan hypothesis consists of a comparison of a relatively short list of words. The similarities revealed by this comparison are superficial, and the evidence falls far short of what would be necessary to warrant confidence in the proposed relationship. By the late 20th century the Aztec-Tanoan hypothesis was mostly abandoned.