Kumeyaay (Kumiai), also known as Central Diegue o, Kamia, and Campo, is the Native American language spoken by the Kumeyaay people of southern San Diego and Imperial counties in California. Hinton (1994:28) suggested a conservative estimate of 50 surviving Kumeyaay speakers. A more liberal estimate (including speakers of Ipai and Tipai), supported by the results of the Census 2000, is 110 people in the US, including 15 persons under the age of 18.
Kumeyaay belongs to the Yuman language family and to the Delta California branch of that family. Kumeyaay and its neighbors, Ipai to the north and Tipai to the south, were often considered to be dialects of a single Diegue o language, but the current consensus among linguists seems to be that at least three distinct languages are present within the dialect chain (e.g., Langdon 1990). Confusingly, Kumeyaay is commonly used as a designation both for the central language of this family and for the Ipai-Kumeyaay-Tipai people as a whole. Tipai is also commonly used as a collective designation for speakers of both Kumeyaay and Tipai proper.
Published documentation for the Kumeyaay language appears to be limited to a few texts (cf. Mithun 1999:578).
Leanne Hinton. 1994. Flutes of Fire: Essays on California Indian Languages. Heyday Books, Berkeley, California.
Langdon, Margaret. 1990. "Diegue o: how many languages?" In Proceedings of the 1990 Hokan Penutian Languages Workshop, edited by James E. Redden, pp. 184 190. University of Southern Illinois, Carbondale.
Mithun, Marianne. 1999. The Languages of Native North America. Cambridge University Press.