Modern scientific usage includes as apes:
Current evidence implies that humans share a common, extinct, ancestor with the chimpanzee/bonobo line, from which we separated more recently than the gorilla line. All living members of the Hylobatidae and Hominidae are tailless, and humans can therefore accurately be referred to as bipedal apes. However there are also primates in other families that lack tails.
Both great apes and lesser apes fall within the infra-order Catarrhini, which also includes the Old World monkeys of Africa and Eurasia. Within this group, both families of apes can be distinguished from monkeys by the number of cusps on their molars (apes have five - the "Y-5" molar pattern, monkeys have only four in a "bilophodont" pattern). Apes have more mobile shoulder joints and arms, ribcages that are flatter front-to-back, and a shorter, less mobile spine compared to monkeys. These are all anatomical adaptations to vertical hanging and swinging locomotion (brachiation) in the apes.
The original usage of "ape" in English may have referred to the baboon, an African monkey. Two tailless species of macaque are commonly named as apes, the Barbary Ape of North Africa (introduced into Gibraltar), Macaca sylvanus, and the Sulawesi black ape or Sulawesi Crested Macaque, M. niger.
Except for gorillas and humans, all true apes are agile climbers of trees. They are best described as omnivorous, their diet consisting of fruit, grass seeds, and in most cases small quantities of meat (either hunted or scavenged), along with anything else available and easily digested. They are native to Africa and Asia.
The intelligence and humanoid appearance of apes are responsible for legends which attribute human qualities; for example, apes are sometimes said to be able to speak but refuse to do so in order to avoid work. They are also said to be the result of a curse -- a Jewish folktale claims that one of the races who built the Tower of Babel became apes as punishment, while Muslim lore says that the Jews of Elath became apes as punishment for fishing on the Sabbath. Christian folklore claims that apes are a symbol of lust and were created by Satan in response to God's creation of humans. It is uncertain whether any of these references is specifically to apes, since all date from a period when the distinction between apes and monkeys was not widely understood, or not understood at all.