'ateles' originates from Ancient Greek, specifically the word 'ἀτέλης' (atelēs), where the prefix 'a-' meant 'not' and 'telēs' meant 'complete' or 'finished'.

'ateles' derived from the Greek adjective 'ἀτέλης' (atelēs, 'incomplete') and was adopted into modern scientific Latin as the genus name 'Ateles' for spider monkeys.

Initially, it meant 'incomplete' or 'imperfect'; over time it became a taxonomic name referring to this group of monkeys (possibly referencing a reduced thumb), losing the general 'imperfect' sense in scientific usage.