According to some authors, the Huilliche language (Huiliche, Williche, Wiliche, Veliche), also known as Chesungun, Chedungun or Chetsungun ("the language of the people"), is considered a dialect or southern variant of the Mapudungu, while others (mostly within the Summer Institute of Linguistics, SIL) refer to it as an independent language, closely related to the former.
This language is spoken in the X Region of the Lakes (Spanish, X Región de Los Lagos, Chile), mostly in the region of San Juan de la Costa (Osorno) and in some remote parts of Chiloé Island. With over 2000 speakers (data of 1982), it is regarded as an endangered language. Huilliche is mainly used by elderly people in family gathering and on ceremonial occasions.
Differences in pronunciation, grammar and vocabulary (highly influenced by Spanish) from Mapudungu have made the Huilliche language difficult to understand for speakers of northern variants of the former.
A great number of the place names of Chiloé Island come from words in Huilliche. Likewise, many of the old customs are still designated in this ancient language, from the chants (kollag) to the gatherings (kengun, kedam), from the fauna and the flora to traditional dishes. Prosecution suffered by this language along the 19th century and for the most part of the 20th century (its use was banned in schools and churches) paved the way for its decline. Not everything is lost, though: at present there are a number of programs whose aim is to recover, safeguard and help restore Huilliche, some of which use traditional music as a vehicle (e.g. The Choir of Huilliche Children of Chiloé).
Chesungun, in Wikipedia.