ROM

Wikipedia also has an article about ROM.

ROM is an abbreviation of Read-Only Memory, a class of computer memory. Because it cannot be modified under normal circumstances, it is mainly used for both software and firmware.

In Game Boy games, ROM addresses (from 4000-7FFF) may also be banked as a work around to many parts of the memory not being available all at once.

ROM can also refer to a ROM image, which is a file containing a copy of the data from a video game cartridge usually intended to be used with a console or emulator.