The term 'Primates Without Tails' refers to a group of primates that do not have tails, such as APES. The four-letter word for this group is 'APES'. APES are a type of primate that includes gorillas, chimpanzees, orangutans, and bonobos. They are distinguished from other primates by their lack of a tail, as well as their larger brains and more complex behavior. APES are found in tropical and subtropical regions of Africa and Asia.