Uakari is the common name for the New World monkeys of the genus Cacajao. Both the English and scientific names are believed to have originated from indigenous languages.The uakaris are unusual among New World monkeys in that the tail length (15-18 cm) is substantially less than their head and body length (40-45 cm). Their bodies are covered with long, loose hair but their heads are bald. They have almost no subcutaneous fat, so their bald faces appear almost skull like.