The term primates refers to a group of mammals that includes APES, monkeys, lemurs, and tarsiers. Primates are characterized by their large brains, flexible hands, and grasping feet. They are also known for their complex social behavior and communication. The four-letter crossword solution for primates is APES, which refers to a subgroup of primates that includes gorillas, chimpanzees, orangutans, and gibbons.