North American Indian language of the Athabascan family, spoken by the Navajo people of Arizona and New Mexico and closely related to Apache. Navajo is a tone language, meaning that pitch helps distinguish words. Nouns are either animate or inanimate. Animate nouns may be “speakers” (humans) or “callers” (plants and animals); inanimate nouns may be corporeal or spiritual. The Navajo fourth person is a grammatical category that enables the speaker to address someone who is present or within hearing distance without naming him or her; because names (name) are thought to have power, the polite form avoids speaking another's name. Gender categories associate maleness with the static and femaleness with the active; thus “thought” (Sá ah Naaghási) is male and “speech” (Biḱ eh Hózhó) is female. Some verb forms vary according to the physical shape of the direct object: for example, the verb form for holding a ball differs from that for holding a stick.

The Navajo language has been tenaciously preserved by its speakers.