The Navajo, also spelled Navaho, are a large Native nation living around Four Corners. They are closely related to the Apache. The Hopi live in an enclave of Navajo land. Navajo call themselves Diné.
In World War II, Navajo code was used by Codetalkers to keep radio messages secret. Navajo is well suited to describing military movements, as its fifteen grammatical numbers indicate not only how many things there are, but also how many groups and whether they are organized. It also has a classifier system indicating shape and mobility.
Navajo has several difficult consonants and consonant clusters. It is tonal; vowels have high or low tone, and if long can also rise or fall. Tone is indicated in writing by an acute accent; nasality is indicated by a mark under the vowel.