Payagua
Payagua was a language isolate once spoken in Paraguay.
An isolate: no relationship to any other known language has been demonstrated.
Payaguá (Payawá) is an extinct language isolate, proposed to be a member of the Mataco–Guaicuru languages, formerly spoken in Paraguay and Argentina by the Payaguá.
From Wikipedia · Payagua language · CC BY-SA 4.0