> The simians (infraorder Simiiformes, Anthropoidea) are the monkeys, cladistically including the apes: the New World monkeys or platyrrhines, and the catarrhin

> The simians (infraorder Simiiformes, Anthropoidea) are the monkeys, cladistically including the apes: the New World monkeys or platyrrhines, and the catarrhine clade consisting of the Old World monkeys and apes. https://en.m.wikipedia.org/wiki/Simian https://en.m.wikipedia.org/wiki/Simian Wikipedia explains it well -- there's no way to form a monkey clade (which includes new world monkeys and old world monkeys) which doesn't include apes. My point was many languages besides English only have a word for the clade, and don't have a specific term for "everything in the clade but apes". The most natural use of "monkey", and the only one with useful biological meaning, is to identify it with the simians in full (as that's the smallest clade which includes everything we think of as monkeys). Of course, that makes apes a kind of monkey.