a single executable that contains a program in versions for both PPC and Intel CPUs

a term used by Apple for "fat" applications which include executable code for both PPC and Intel processors

the term used for an application (like Interarchy 8) that is native for both PowerPC and Intel Macs.

A universal binary is, in Apple parlance, an application bundle that runs natively on either Power PC- or x86 (Intel)-based Macintosh computers. It was introduced at the 2005 WWDC as a means to ease the transition from the existing PowerPC architecture to systems based on Intel processors, which began shipping in 2006. Universal binaries typically include both PowerPC and x86 versions of a compiled application.