Kutenai is a language isolate. There have been attempts to place Kutenai in either a Macro-Algonquian or Macro-Salishan language family, most recently with Salish, but these have not been generally accepted as proven.
Like other northwest languages, Kutenai has a rich inventory of consonants and a small inventory of vowels. However, there do exist other allophones of the three basic phonemic vowels. The lack of a phonemic distinction between voiced and voiceless consonants is much like other languages of the interior northwest. Due to Kutenai's location on the periphery of the northwest linguistic area, the loss of a rich lateral inventory is consistent with other interior northwest languages which today have only one or two lateral consonants. One such language group contains the Sahaptian languages which have had a similar loss of laterals. Nez Perce has /ts/ which was the lateral affricate in the proto-language. Nez Perce, like Kutenai, also lies in the eastern periphery of the Northwest Linguistic area. Another typological analysis investigates the lexical category of preverbs in Kutenai. This lexical category is distinctive of neighboring Algonquian languages which are located just on the other side of the Kootenay mountains, neighboring the Kutenai linguistic area. Another typological relationship Kutenai could have is the presence of its obviation system.
In 1991 Lawrence Richard Morgan wrote a description of the Kutenai Language as his PhD dissertation through the University of California, Berkeley. This description is focused on how the language works and specifically what are the working parts of the language. Morgan's work is an exhaustive list of each grammatical particle, morpheme, and affix with their respective environments and their varying forms.
Vowel length in Ktunaxa is also contrastive, meaning it's possible to differentiate between two otherwise identical words just by lengthening or shortening a vowel. Some such minimal pairs are the verbal stem 'to dig something up' [ʔakaːkʼuː] and the noun '(steel animal) trap' [ʔaːkaːkʼuː] and the verbal stem for 'to fall out in this direction/to fall out from somewhere' [ʔakmuːxuː] and 'the place where (someone is) sitting, one's place at a table' [ʔaːkmuːxuː]. Both pairs differ only in the length of the first vowel, [a] vs [a:].
In general terms, Kutenai is an agglutinative language, with many grammatical functions being served by both prefixes and suffixes, primarily on the verb (though there are some affixes that select nouns, as well). As mentioned above, a distinctive feature of Kutenai is its use of an obviation system as a way to track which entities and concepts are particularly central/salient to a story being told, as well as as a grammatical way of clarifying the roles of each entity in sentences with two third-person arguments. "Pronouns, nouns, verbs, and adverbs all take obviative markers," making it particularly different from some more well-known obviation systems (like the Algonquian one, which allows for obviation only on third-person animate nouns). Kutenai also makes use of an inverse system. The language has an overt copula, ʔin `to be'.
Word order in Kutenai can be flexible in response to discourse and pragmatic concerns. As is the case with many head-marking languages, it is rare to have both an overt subject and an overt object in a sentence, since the morphology on the verb makes it clear who is acting on whom. Morgan states that when in cases where it is appropriate to express both arguments of a verb in a "neutral" context, VOS word order is preferred; however, it also alternates with VSO order. The pre-verbal position can be occupied by adverbs, as seen in the following three examples:
The old lady started looking for lice.
Long ago there was a man named `Xaxa' (or Crow).
Crow loves Naʔuti.
One aspect of Kutenai that complicates these word order facts somewhat is the fact that the verb is marked for first- or second-person subjects by "affixal or clitic pronouns" that precede the stem, hu/hun for `I' and hin for `you'. It is common in the orthography to write these pronouns as separate words, making it seem as though the word order is Subject Pronoun + Verb (+ Object).
In many languages, conditions for inverse include situations where the first or second person is in the "object" role, and the third person is the "subject" as in `She saw you/me.' In Kutenai, however, these situations use specific "first-/second-person object" morphology, separate from the inverse. As a consequence of this, Kutenai's inverse system is most clearly observable in interactions between third persons. The following two examples (from Dryer 1991) show the direct and inverse, respectively:
Kutenai subordinate/dependent clauses are marked with a k and a lack of indicative morphology on the verb, as are questions, nominalizations, and relative clauses. This k can cliticize to the material that follows it, as seen in the example below.
He saw a man doing something in a hurry. (He saw him, a man that he does something quickly.)
^Marianne Mithun. The Languages of Native North America (1999, Cambridge).
^Lyle Campbell. American Indian Languages: The Historical Linguistics of Native America (1997, Oxford).
^Dryer, Matthew S. 2002. A comparison of Preverbs in Kutenai and Algonquian. In D. Pentland (Ed.), Proceedings of the Thirtieth Algonquian Conference (pp. 63-94). Winnipeg: University of Manitoba.
^Dryer, Matthew S. 2007. Kutenai, Algonquian, and the Pacific Northwest from an areal perspective. In H. Wolfart (Ed.), Proceedings of the Thirty-Eighth Algonquian Conference (pp. 155-206). Winnipeg: University of Manitoba.
^Dryer, Matthew S. 1992. "A comparison of the obviation systems of Kutenai and Algonquian." Papers of the 23rd Algonquian Conference. Ottawa: Carleton.
^ abMast, Susan J. 1988. "Aspects of Kutenai Morphology." Master's Thesis, University of Pittsburgh.
^ abDryer, Matthew S. 1991. "Subject and Inverse in Kutenai." Occasional papers on linguistics No. 16, Proceedings from the American Indian Languages Conference edited by James E. Redden. (Conference held at the University of California at Santa Cruz.)
^Dryer, Matthew S. 1994. "The discourse function of the Kutenai inverse." Voice and inversion 28 (1994): 65.
Dryer, Matthew S (2002) A Comparison of Preverbs in Kutenai and Algonquian. In Proceedings of the Thirtieth Algonquian Conference, edited by David Pentland, pp. 63–94. Winnipeg: University of Manitoba.
Dryer, Matthew S. (2007) "Kutenai, Algonquian, and the Pacific Northwest from an areal perspective". In, Proceedings of the Thirty-Eighth Algonquian Conference, edited by H. C. Wolfart, pp. 155–206. Winnipeg: University of Manitoba. ISSN0831-5671