Def extension is associated with Module-Definition file. You have chance to open def files with Visual C++ or C++ Builder softwares.
Def extension stands fr DLL list files. These file types are used by program developers. While creating DLL, it is a file that used for link and export details of Visual C++ kind of softwares. You have chance to open def files with Visual C++ or C++ Builder software. You can get detailed information about the softwares from the following link of microsoft.com
What to use def
Visual C++ , C++ Builder
which page related to def file
def Related Searches
You can check related links about def fileextension.