The Guató language, or , is a possible language isolate

Language isolate

A language isolate, in the absolute sense, is a natural language with no demonstrable genealogical relationship with other languages; that is, one that has not been demonstrated to descend from an ancestor common with any other language. They are in effect language families consisting of a single...

 spoken by the about 10% Guató people of Brazil. Kaufman (1990) provisionally classifies it as a branch of the Macro-Gê languages

Macro-Gê languages

Macro-Jê is a medium-sized language stock in South America centered around the Jê language family, with all other branches currently being single languages due to recent extinctions. The family was first proposed in 1926, and has undergone moderate modifications since then...

, but no evidence for this was found by Eduardo Ribeiro.

Phonology

The Guato vowel system, like that of other Macro-Je languages, collapses a three-way distinction of height in oral vowels to two in nasal vowels.

	oral			nasal
	front	central	back	front	central	back
close	i	ɨ	u	ĩ	ɨ̃	ũ
mid	e		o	ẽ	ã
open	ɛ	a	ɔ

	labial	dento- alveolar	post- alveolar	velar	labio- velar	glotal
nasal	m	n
voiced plosive	b	d	dʒ	ɡ	ɡʷ
voiceless plosive	p	t	tʃ	k	kʷ
fricative	f					h
sonorant	w	ɾ	j