MAME 0.139 is a version of the MAME emulator released on January 27, 2011. A ROMset, short for "ROM collection," refers to a set of files containing the data from arcade game cartridges, disks, or other media. In this case, the MAME 0.139 ROMset contains the necessary files to play a wide range of arcade games on MAME version 0.139.