Tennis elbow is the layperson term for lateral epicondylitis which means inflammation
of the boney prominence on the outside of your elbow (your lateral epicondyle).
This is a very common injury in racquet players and has therefore claimed the name “tennis elbow”. If you don’t play any racquet sports, understandably it seems strange to have developed this type of injury. However, prolonged mouse and keyboard use is also a common activity amongst people that develop this irritation.