Definition data
File type: Various data file
Files with def extension are usually encountered as definition files used SmartWare, Visual Studio and other apps.
Found 6 different file type records with the same def filename suffix.
File type category:
Various data file
Date updated: September 9, 2024
File extension def is commonly used for so called definition files. These file contains various settings that define certain characteristic ,or operation parameters for programs, devices or their part. Such files are used by many different programs. Sometimes also used for export purposes.
For example module-definition files provide the linker with information about exports, attributes, and other information about the program to be linked. The def file is most useful when building a DLL.
Use Visual Studio and other tools to work with *.def files.
Conversion to other formats is not possible.
Software applications that can open def files:
Microsoft Windows
Software applications that can edit def files:
Microsoft Windows
Software capable of saving def files:
Microsoft Windows
Software apps that create def files:
Microsoft Windows
Linux/Unix
Multiplatform
Software applications that handle other tasks involving def files:
Microsoft Windows
Linux/Unix
Multiplatform
Microsoft MS-DOS
File type category:
Various data file
Date updated: September 18, 2017
The def file extension is associated with the Data Entry & Review Module application that helps users to automate the flow of data. The .def file contains various data used for internal purposes of the Data Entry/Review Module application.
Software applications that handle other tasks involving def files:
Microsoft Windows
File type category:
Settings, options, themes or skins file
Date updated: September 28, 2026
The DEF file extension is associated with ESwin, Spanish engineering software from Procedimientos-Uno.
An ESwin DEF file contains wizard-related data, such as settings or other information required by an ESwin wizard.
ESwin and this file type are intended for Microsoft Windows. The format is specific to ESwin.
Open an ESwin DEF file with ESwin on Microsoft Windows, where the relevant wizard can use the file.
A DEF file may not provide useful information when opened independently because it contains wizard-related ESwin data.
ESwin DEF files are intended for use by ESwin rather than as interchange documents.
If data must be moved to another format, open the file in ESwin and use an export or save option provided by the relevant wizard, if available.
Software apps that manage or store settings in def files:
Microsoft Windows
ESwin
Software applications that handle other tasks involving def files:
Microsoft Windows
ESwin
File type category:
Game file
Date updated: May 22, 2019
The def file extension is associated with the id Tech 6 a video gaming engine, developed by id Software for Doom (Doom 4, Doom 2016) video game.
The def file contains video card (graphic card) settings. These files are included in resources game archive.
Probably not meant to be accessed by the user.
Probably cannot be converted to anything else.
Software apps that manage or store settings in def files:
Multiplatform
File type category:
Various data file
Date updated: October 5, 2026
The def file extension is associated with IObit Malware Fighter, Windows security software from IObit. Malware Fighter can use these definitions to identify and remove malware from a PC.
A def file contains malware definitions for Malware Fighter. The data supports the program's detection functions rather than serving as a document intended for direct user editing.
These files are used as part of Malware Fighter's installed data. Their contents are specific to the software and may be replaced when the program receives updated malware definitions.
On Microsoft Windows, open this file with IObit Malware Fighter if the software provides an associated opening action. In normal use, Malware Fighter reads the file automatically, and it is not intended to be opened as a document or edited in a text editor.
There is no useful general-purpose conversion for an IObit Malware Fighter definition file. The data is intended for use by Malware Fighter and should not be converted to another document or data format.
To obtain a different or newer set of definitions, use Malware Fighter's own update function rather than attempting to convert the def file.
Software applications that handle other tasks involving def files:
Microsoft Windows
File type category:
Game file
Date updated: February 12, 2019
The def file extension is also used in NovaLogic game engine (Voxel Space engine - Delta Force series, and other video games) for files that contain weapon profiles, item profiles, etc.
Software applications that handle other tasks involving def files:
Microsoft Windows
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