DEF File
What are DEF files and how to open them
Are you having problems opening a DEF file or just wondering what they contain? We explain what these files are used for and show you software that we know can open or otherwise handle your files.
What is a DEF file?
DEF files have multiple uses, and 22DISK Format Definition is one of them. Read more about the other uses further down the page.
22DISK Format Definition File
We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.
How to open DEF files
Important: Different programs may use files with the DEF file extension for different purposes, so unless you are sure which format your DEF file is, you may need to try a few different programs.
While we have not verified the apps ourselves yet, our users have suggested ten different DEF openers which you will find listed below.
Last updated: January 19, 2023
All known file formats using extension .DEF
While 22DISK Format Definition File is a popular type of DEF-file, we know of 6 different uses of the .DEF file extension. Different software may use files with the same extension for different types of data.
Module-Definition File
Files that contain the .def file extension are most commonly associated with Microsoft Visual C++ definition files. These files list the exports and attributes of a specific program that is linked by an application linker.
The DEF file format is commonly used when creating a dynamic link library during the development of a software application.
DEF opener for Windows
We have identified one DEF opener that is compatible with this specific type of DEF file.
![]() | Microsoft Visual Studio | Verified |
More file formats using the DEF extension
Through our research of DEF files, we know that the following formats exist. However, we have not yet analyzed them in detail.
- Chinese UCDOS Print Definition File
- Personal Font Maker Definition File
- Philips Ease Database Definition File
- ThunderByte Antivirus Definitions
Various apps that use files with this extension
These apps are known to open certain types of DEF files. Remember, different programs may use DEF files for different purposes, so you may need to try out a few of them to be able to open your specific file.
![]() | Army Builder | User submitted |
![]() | progeCAD Professional | User submitted |
![]() | Movie Magic Screenwriter | User submitted |
![]() | WinEdt | User submitted |
![]() | MapBasic | User submitted |
![]() | Untis | User submitted |
![]() | Open Watcom | User submitted |
![]() | Evaluation Flash | User submitted |
![]() | IrfanView | User submitted |
![]() | ABCreator for Army Builder | User submitted |
Help us help others
File.org helps thousands of users every day, and we would love to hear from you if you have additional information about DEF file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.
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