Mandan (Mandan: Nų́ų́ʔetaa íroo) is an extinct Siouan language of North Dakota in the United States.

By 2009, there was just one fluent speaker of Mandan, Dr. Edwin Benson (1931–2016).^[2] The language is being taught in local school programs to encourage the use of the language.^[3] Prior to Benson's death, Estonian linguist Indrek Park worked with him for more than two years to preserve the language as much as possible.^[4] The 2020 documentary To Save A Language portrays Park's efforts to revive the language.^[5]

Mandan is taught at Fort Berthold Community College along with the Hidatsa and Arikara languages.^[2] Linguist Mauricio Mixco of the University of Utah has been involved in fieldwork with remaining speakers since 1993. As of 2007, extensive materials in the Mandan language at the college and at the North Dakota Heritage Center, in Bismarck, North Dakota, remained to be processed, according to linguists.^[6]

The MHA Language Project has created language learning materials for Mandan, including a vocabulary app, a dictionary, and several books in the language. They also provide a summer learning institute and materials for teachers.^[7]

Mandan was initially thought to be closely related to Hidatsa and Crow. However, since Mandan has had language contact with Hidatsa and Crow for many years, the exact relationship between Mandan and other Siouan languages (including Hidatsa and Crow) has been obscured and is currently undetermined. Thus, Mandan is most often considered to be a separate branch of the Siouan family.

Mandan has two main dialects: Nuptare and Nuetare.

Only the Nuptare variety survived into the 20th century, and all speakers were bilingual in Hidatsa. In 1999, there were only six fluent speakers of Mandan still alive.^[8] Edwin Benson, the last surviving fluent Mandan speaker, died in 2016.^[9]

The language received much attention from White Americans because of the supposedly lighter skin color of the Mandan people, which they speculated was due to an ultimate European origin. In the 1830s Prince Maximilian of Wied spent more time recording Mandan over all other Siouan languages and prepared a comparison list of Mandan and Welsh words (he thought that the Mandan might be displaced Welsh).^[10] The idea of a Mandan/Welsh connection was also supported by George Catlin.^[11]

Will and Spinden (p. 188) report that the medicine men had their own secret language.

Mandan has the following consonant phonemes:

/w/ and /r/ become [m] and [n] before nasal vowels, and /r/ is realized as [ⁿd] word-initially.^[12]

Mandan is a subject–object–verb language.

Mandan has a system of allocutive agreement and so different grammatical forms may be used that depend on the gender of the addressee. Questions asked of men must use the suffix -oʔsha: the suffix -oʔną is used to ask of women. Likewise, the indicative suffix is -oʔsh to address men, -oʔre to address women. The same goes for the imperative: -ta (male), -ną (female).^[13]

Mandan verbs include a set of postural verbs, which encode the shapes of the subject of the verb:^[14]

The English translations are not "A pot was sitting there," "A big village stood there," or "The river lay there." That reflects the fact that the postural categorization is required in such Mandan locative statements.

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Mandan, like many other North American languages, has elements of sound symbolism in its vocabulary. A /s/ sound often denotes smallness/less intensity, /ʃ/ denotes medium-ness, /x/ denotes largeness/greater intensity:^[15]

• síire "yellow"
• shíire "tawny"
• xíire "brown"
• seró "tinkle"
• xeró "rattle"

Compare the similar examples in Lakhota.