Betoi-Jirara
Betoi-Jirara was a language isolate once spoken in Venezuela.
An isolate: no relationship to any other known language has been demonstrated.
Betoi–Jirara is an extinct, unclassified and poorly attested dialect cluster of Colombia and Venezuela, south of the Apure River near the modern border with Colombia.
From Wikipedia · Betoi–Jirara language · CC BY-SA 4.0
Most similar languages
Vocabulary compares 40 basic words (ASJP); grammar compares 195 features (Grambank). Similar is not always related.