Hidatsa hɪˈdɑːtsə is an endangered Siouan language that is related to the Crow language. It is spoken by the Hidatsa tribe, primarily in North Dakota and South Dakota. A description of Hidatsa-Mandan culture, including a grammar and vocabulary of the language, was published in 1877 by Washington Matthews, a government physician who lived among the Hidatsa at the Fort Berthold Indian Reservation. More recently, the language has been the subject of work in the generative grammar tradition. In 2019, it was estimated that there were less than 65 fluent speakers of the language. Linguists working on Hidatsa since the 1870s have considered the name of Sacagawea, a guide and interpreter on the Lewis and Clark Expedition, to be of Hidatsa origin. The name is a compound of two common Hidatsa nouns, cagáàga tsaɡáàɡa 'bird' and míà [míà] 'woman'. The compound is written as Cagáàgawia 'Bird Woman' in modern Hidatsa orthography and pronounced tsaɡáàɡawia (/m/ is pronounced [w] between vowels in Hidatsa). The double /aa/ in the name indicates a long vowel and the diacritics a falling pitch pattern. Hidatsa is a pitch-accent language that does not have stress so all syllables in [tsaɡáàɡawia] are pronounced with roughly the same relative emphasis. However, most English speakers perceive the accented syllable (the long áà/) as stressed. In faithful rendering of the name Cagáàgawia to other languages, it is advisable to emphasize the second, long syllable, not the /i/ vowel, as is common in English. Primary stress in Hidatsa is predictable and occurs on the first quantity sensitive iamb of the word. Initial heavy syllables result in stress on the first syllable, while initial light syllables result in stress on the second syllable. The vowels of stressed syllables are significantly louder than those of surrounding syllables and of their unstressed counterparts. Hidatsa has five vowels and two diphthongs. It lacks nasal vowels, which is a way it differs from other Siouan languages. (Boyle 2007) The /a/ vowel has three sounds.