Sahaptin (suh-HAP-tin), also called Ichishkiin (ih-chis-KEEN; Umatilla: Čiškíin, Yakama: Ichishkíin Sɨ́nwit), is one of the two-language Sahaptian branch of the hypothetical Plateau Penutian family spoken in a section of the northwestern plateau along the Columbia River and its tributaries in southern Washington, northern Oregon, and southwestern Idaho, in the United States;[2] the other language is Nez Perce (Niimi'ipuutímt).

[6] The words Sahaptin, Shahaptin, and Sahaptian are derived from the Columbia-Moses name for the Nez Perce, sħáptənəxʷ.

[10] The first usage of the word "Sahaptin" dates to 1811, in the journal of fur trader David Thompson, who wrote of the "Chief of all the Shawpatin Tribes", referring to the Nez Perce.

[15][16] Sahaptin has a split ergative syntax, with direct-inverse voicing and several applicative constructions.

q̓ínusee-šana-ASP=maš=1SG/2SGq̓ínu -šana =mašsee -ASP =1SG/2SG'I saw you'pá-INV-q̓inusee-šana-ASP=nam=2SGpá- q̓inu -šana =namINV- see -ASP =2SG'you saw me'In Speech Act Participant (SAP) and third-person transitive involvement, direction marking is as follows: á-OBV-q̓inusee-šana-ASP=aš=1SGpaanáy3SG.ACCá- q̓inu -šana =aš paanáyOBV- see -ASP =1SG 3SG.ACC'I saw him/her/it'i-3.NOM-q̓ínusee-šana-ASP=aš=1SGpɨ́nɨm3.ERGi- q̓ínu -šana =aš pɨ́nɨm3.NOM- see -ASP =1SG 3.ERG'he/she/it saw me'