The first written vocabulary of the Cayuse language was published by Horatio Hale in 1846. As a member of the United States Exploring Expedition, he had visited the Pacific Northwest in 1841. Missionary Marcus Whitman was credited for providing "much valuable information" about the Cayuse people and other natives nearby Waiilatpu.3 Whitman was credited as the origin of the Waiilatpuan linguistic family. In his Waiilatpuan language family, Hale put Cayuse and the Molala language as the sole members.4
In 1910 or 1911, Stephens Savage, a Molala speaker, had told Leo Frachtenberg that the following five words were identical in both Cayuse and Molala:5
In 1929 Edward Sapir grouped Cayuse with Molala as part of the Waiilatpuan branch of the Plateau Penutian languages.6
Bruce Rigsby reexamined the Cayuse-Molala lexical pairs provided by Hale in 1969 and found only a tenth to be potentially related terms. The words presented by Savage were concluded by Rigsby to likely be loanwords. Upon his review of extant Molala and Cayuse linguistic data, Rigsby concluded "I do not see how the two languages could have possibly been mutually intelligible."7
Cayuse pronouns listed by Hale:8
Cayuse pronouns listed by McBean:9
Cayuse verb paradigms documented by Henry W. Henshaw:10
Limited lexical items in Cayuse have been collected by Rigsby, Melville Jacobs, Verne Ray, and Theodore Stern. Their Cayuse informants had highly limited knowledge of the language and were more fluent in either Sahaptin or Nez Perce.
A word list of Cayuse with nearby 200 lexical items was documented by Hale.11 The word list has been reproduced below.
Campbell, Lyle (2024-06-25), "North American Indian Languages North of Mexico", The Indigenous Languages of the Americas (1 ed.), Oxford University PressNew York, pp. 28–145, doi:10.1093/oso/9780197673461.003.0002, ISBN 978-0-19-767346-1, retrieved 2025-06-25 978-0-19-767346-1 ↩
Aoki 1998. - Aoki, Haruo (1998). A Cayuse Dictionary based on the 1829 records of Samuel Black, the 1888 records of Henry W. Henshaw and others. Mission, OR: Confederated Tribes of the Umatilla Indian Reservation. ↩
Hale 1846, p. 542. - Hale, Horatio (1846). Ethnography and Philology. Philadelphia: C. Sherman – via Internet Archive. https://archive.org/details/Ethnographyphil00Hale ↩
Hale 1846, p. 561. - Hale, Horatio (1846). Ethnography and Philology. Philadelphia: C. Sherman – via Internet Archive. https://archive.org/details/Ethnographyphil00Hale ↩
Rigsby 1969. - Rigsby, Bruce (Spring 1969). Sprague, Roderick; Goss, James A. (eds.). "The Waiilatpuan Problem: More on Cayuse-Molala Relatability". Journal of Northwest Anthropology. 3 (1): 68–146 – via Google Books. https://books.google.com/books?id=_s2-DwAAQBAJ&pg=PA68 ↩
Sapir 1929. - Sapir, Edward (1929). "Central and South American Languages". Encyclopedia Britannica. Vol. 5 (14th ed.). pp. 138–141. ↩
Rigsby 1969, pp. 82–83. - Rigsby, Bruce (Spring 1969). Sprague, Roderick; Goss, James A. (eds.). "The Waiilatpuan Problem: More on Cayuse-Molala Relatability". Journal of Northwest Anthropology. 3 (1): 68–146 – via Google Books. https://books.google.com/books?id=_s2-DwAAQBAJ&pg=PA68 ↩
Hale 1846, pp. 570–629. - Hale, Horatio (1846). Ethnography and Philology. Philadelphia: C. Sherman – via Internet Archive. https://archive.org/details/Ethnographyphil00Hale ↩