Definition: fat binary

Software that is distributed in two formats in order to ease transition to a new hardware architecture. For example, when Apple switched from Motorola 68K CPUs to PowerPC (PPC) chips in 1994, it provided a fat binary format containing both 68K and PPC machine languages. Again in 2006 when Apple switched from PPC to Intel chips, it created a PPC/Intel fat binary, dubbed the "universal binary."