File Extension/DEF
alphabetical list of extensions

File extension .DEF

Description of the problem
If you have on your computer a .DEF file that you cannot open, you are in exactly the same situation as thousands of other people who have similar problems with this or any other unknown file.

There may be several reasons why you cannot open the file with .DEF extension. Directly on this website you can find a solution of the most common problem with the .DEF file – that you do not have on your computer the appropriate program to open the file.
Solution
From the list below, select the appropriate program, install it and double click on the icon of a file that did not want to open - the problem with the .DEF file extension should be solved. However, if this does not happen, go back to the website to learn about other possible causes of the error, which have been described at the bottom of the website.
Category
Developer Files
Developer
N/A
Popularity
StarStarStar
File name: Module-Definition File
Programs that will open this file:
Windows
Windows
AniSprite AniSprite
ArcGIS for Desktop Basic (ArcView) ArcGIS for Desktop Basic (ArcView)
AutoCAD AutoCAD
SmartWare SmartWare
SmartWare II SmartWare II
Visual C++ Visual C++
Visual Studio Visual Studio
Linux
Linux
DataFlex DataFlex
Category
Spreadsheet Files
Developer
SmartWare
Popularity
StarStar
File name: SmartWare II Data File
Programs that will open this file:
Windows
Windows
SmartWare SmartWare
Category
Game Files
Developer
Elecbyte
Popularity
Star
File name: M.U.G.E.N. Character Definition File
Programs that will open this file:
Windows
Windows
M.U.G.E.N. M.U.G.E.N.
Category
Data Files
Developer
IObit
Popularity
Star
File name: IOBit Malware Fighter Definitions File
Programs that will open this file:
Windows
Windows
Malware Fighter Malware Fighter
Remember!
The .DEF file extension can correspond to several not related file formats. If there is more than one file format with the .DEF extension, you will probably find most of them at this website. Remember that you need to download a program to support a particular file type. So first look through the entire contents of the website to select a program to support just the file you have.

Other possible reasons why your .DEF file does not want to open

In addition to the problem described above, i.e. the lack of the appropriate application to support the .DEF file, there may be several reasons that cause problems with opening and operation of the data format:

1. Incorrect version of the installed application

A quite common problem is the lack of application in the appropriate version. Even if you have an application, with the help of which you should open the .DEF file, you may have a problem with it because of its version. Perhaps in previous versions the application has not yet supported the .DEF file, so download the update and check again.

2. Incorrect .DEF file association with the program

If you have already installed the appropriate application, and it is the correct version, the file may not open correctly, because the operating system does not have information that this program supports the file. So you need to "show" which program the computer should use. To do this:

  • Right-click the .DEF file
  • Go to the "Open with" - then "Choose default program ..."
  • Locate the appropriate application
  • Click "OK"

3. The file is corrupt

It also happens that the file you want to open is corrupt and therefore there is no such possibility. In this situation, you should find its different version, or ask a person from whom you got, to send it again.