Wiktionary
game port
n. (context computing English) An I/O port, on earlier PCs, used for the attachment of a joystick or similar hardware
Wikipedia
Game port
The game port, originally introduced on the Game Control Adapter, is a device port that was found on IBM PC compatible and other computer systems throughout the 1980s and 1990s. It was the traditional connector for joystick input and MIDI devices, until replaced by USB in the 21st century.
Originally located on a dedicated expansion card, the game port was later integrated with PC sound cards, and still later on the PC's motherboard. During the transition to USB, many input devices used the game port and a USB adaptor in the form of a cable expansion.