Sahaptin or Shahaptin, endonym Ichishkin,^[2] is one of the two-language Sahaptian branch of the 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;^[3] the other language is Nez Perce or Niimi'ipuutímt.

The word Sahaptin/Shahaptin is not the one used by the tribes that speak it, but from the Columbia Salish name, Sħáptənəxw / S-háptinoxw, which means "stranger in the land". This is the name Sinkiuse-Columbia speakers traditionally called the Nez Perce people.^[4] Early white explorers mistakenly applied the name to all the various Sahaptin speaking people, as well as to the Nez Perce. Sahaptin is spoken by various tribes of the Washington Reservations; Yakama, Warm Springs, Umatilla; and also spoken in many smaller communities such as Celilo, Oregon.

The Yakama tribal cultural resources program has been promoting the use of the traditional name of the language, Ichishkíin Sɨ́nwit ('this language'), instead of the Salish term Sahaptin.^[5]

In the Handbook of North American Indians, Sahaptin was split in the following dialects and dialect clusters:^[6]

The charts of consonants and vowels below are used in the Yakima Sahaptin (Ichishkiin) language:^[7]

This writing system is used for Umatilla Sahaptin.

Other works use the Yakima practical alphabet.^[7]

There are published grammars,^[9][6] a recent dictionary,^[5] and a corpus of published texts.^[10][11]

Sahaptin has a split ergative syntax, with direct-inverse voicing and several applicative constructions.^[12]

The ergative case inflects third-person nominals only when the direct object is first- or second-person (the examples below are from the Umatilla dialect):

The direct-inverse contrast can be elicited with examples such as the following. In the inverse, the transitive direct object is coreferential with the subject in the preceding clause.

The inverse (marked by the verbal prefix pá-) retains its transitive status, and a patient nominal is case marked accusative.

A semantic inverse is also marked by the same verbal prefix pá-.

In Speech Act Participant (SAP) and third-person transitive involvement, direction marking is as follows:

• Sahaptian languages
• Sahaptin people
• Cayuse
• Palus (tribe)
• Umatilla (tribe)
• Walla Walla (tribe)
• Yakama