The Nahuan or Aztecan languages are those languages of the Uto-Aztecan

Uto-Aztecan languages

Uto-Aztecan or Uto-Aztekan is a Native American language family consisting of over 30 languages. Uto-Aztecan languages are found from the Great Basin of the Western United States , through western, central and southern Mexico Uto-Aztecan or Uto-Aztekan is a Native American language family...

 language family

Language family

A language family is a group of languages related through descent from a common ancestor, called the proto-language of that family. The term 'family' comes from the tree model of language origination in historical linguistics, which makes use of a metaphor comparing languages to people in a...

 that have undergone the sound change

Sound change

Sound change includes any processes of language change that affect pronunciation or sound system structures...

 known as Whorf's Law changing the original /*t/ to [tɬ] before */a/. Subsequently some Nahuan languages have changed /tl/ back to /t/ or to /l/, but it can still be seen that the language went through a -tl stage.

The Nahuan are the extinct Pochutec language and the various Nahuatl dialects

Nahuatl dialects

The many dialects of the Nahuatl language belong to the Nahuan branch of the Uto-Aztecan language family, and form a group of linguistic varieties spoken in central Mexico...

, including Pipil

Pipil language

Pipil is a Uto-Aztecan language descended from Nahuatl which was spoken in several parts of present day Central America before the Spanish conquest. It is on the verge of extinction in western El Salvador and has already gone extinct elsewhere in Central America...

.