The term 'Frequently Injured Joint' can be summarized as a joint that is prone to injury. The most common joint that falls into this category is the KNEE, which is a four-letter word. The KNEE is a joint that connects the thigh bone to the lower leg bones and is responsible for supporting the body's weight when standing, walking, running, and jumping. It is also the largest joint in the body and is vulnerable to injury due to its complexity and the amount of stress it is subjected to.