A CrossCompiler is a Compiler capable of generating BinaryExecutables for a platform other than that on which it currently runs. GCC can be a CrossCompiler if correctly setup.
For example, you can compile up GCC so that it creates Win32 executables when running on Linux, so you don't even have to go near a MicrosoftWindows computer during development. Coupled with a CrossPlatform GUI like wxWidgets, you can use the same SourceCode and MakeFiles to create native applications for multiple platforms all from the comfort of your Linux box.
See also:
One page links to CrossCompiler: