Tereno is a Tupí-Guaraní language spoken in Brazil. It is one of the most divergent Tupí-Guaraní languages, with only about 10% of its vocabulary being shared with other Tupí-Guaraní languages.
The Tereno people live in the states of Mato Grosso and Mato Grosso do Sul in Brazil. There are an estimated 4,000 speakers of Tereno, which is also known as Terêna.
Tereno is a tonal language, with two levels of tone. It has a complex system of verb inflection, with verbs taking on different suffixes depending on the subject, object, and other factors.
The Tereno language is endangered, with only about half of the Tereno people today being able to speak it. Many Tereno children are not learning the language, instead opting to speak Portuguese, which is the language of education and commerce in Brazil.
The Tereno language has been described as "musical" and "melodic", and it is known for its use of onomatopoeia.