Monkey Loves The Cat

The term 'monkey' is an artificial grouping; it is not a "good" taxon, but instead it is a paraphyletic group, like "fish". A "good" taxon, as most modern biologists consider it, is a monophyletic group, that is, a group consisting of all the evolutionary descendants of a single ancestor species. The term 'monkey' covers all platyrrhines (flat, broad noses) and some catarrhines (nostrils-downwards), but excludes the apes.
Due to its size (up to 1 m/3 ft) the Mandrill is often thought to be an ape, but it is actually an Old World monkey. Also, a few monkey species deceptively have the word "ape" in their common name, such as the Barbary Ape.
A group of monkeys may be referred to as a mission or a tribe.