DEF file format description

Many people often share .def files without providing instructions on how to use them. This can make it difficult for users to determine which program is compatible for editing, converting, or printing .def files. To address this issue, we have created this page to offer assistance and guidance on handling .def files. We provide information on compatible software, editing instructions and conversion options to help users effectively interact with .def files.

Our aim is to simplify the process and promote seamless use of the .def file format.

8 filename extension(s) found in our database.

.def - C++ Definition File

The DEF development files are related to Visual C++. The DEF file is a C++ Definition File. C++ is a general-purpose programming language. It is a statically-typed free-form multi-paradigm language supporting procedural programming, data abstraction, object-oriented programming, and generic programming.

Application:Visual C++
Category:Development files
Magic:- / -

C++ Definition File related extensions:

  • lbr Micro Focus COBOL Data
  • link Eclipse Link File
  • ohl Delphi OpenHelp Links
  • rem Delphi Memory Swap Data
  • hxv MS Help 2 Project Virtual Topic Definition
  • 2lang 2LANG Data

.def - Binary Editor Definition Data

The DEF configuration files are related to Binary Editor. The DEF file is a Binary Editor Definition Data. The Binary Editor software allows for editing of the Ford EEC binary data. Its definition files (Strategy Files) are open source and are saved in Excel.

Application:Binary Editor
Category:Configuration files
Magic:- / -

Binary Editor Definition Data related extensions:

  • fcfg Fedora Server Configuration Data
  • hgrc Mercurial Configuration Data
  • ehil Evozi HTTP Injector Lite Data
  • sll SpectraLayers Pro Layout Settings
  • aus Outpost Firewall Pro Configuration
  • axc Microsoft Dynamics AX Configuration

.def - SmartWare Definition Data

The DEF data files are related to SmartWare. The DEF file is a SmartWare Definition Data. SmartWare is a programming platform. SmartWare also includes a word processor, spreadsheet, and communication modules.

Category:Data files
Magic:- / -

SmartWare Definition Data related extensions:

  • aif SmartWare Executable Program
  • bdc SmartWare Word Processor Backup Data
  • bdf SmartWare Backup Definition Data
  • bfq SmartWare Backup Query Definition
  • bfr SmartWare Backup Report Definition
  • bfs SmartWare Sort Definition Backup

.def - Doom 3 Map Definition Data

The DEF game data files are related to Doom 3. The DEF file is a Doom 3 Map Definition Data. Doom 3 is a science fiction survival horror first-person shooter video game developed by id Software.

Application:Doom 3
Category:Game Data files
Magic:- / -

Doom 3 Map Definition Data related extensions:

  • drs Age of Empires 2 Game Data
  • ftl Faster Than Light Mod Data
  • resdex Stronghold 3 Resource Data
  • ttg Red Alert 3 Game Data
  • cvm Odin Sphere Game Data
  • w3z Warcraft 3 Saved Game

.def - IOBit Malware Fighter Definitions Data

The DEF data files are related to IOBit Malware Fighter. The DEF file is an IOBit Malware Fighter Definitions Data. IObit Malware Fighter is an anti-malware and anti-virus program.

Application:IOBit Malware Fighter
Category:Data files
Magic:- / -

IOBit Malware Fighter Definitions Data related extensions:

  • gba Nintendo GameBoy Advance ROM Image
  • aa4 Clone Manager Assembly Results Data
  • bch PCCharge Offline Transaction Log
  • hyv CARE-S InfoWorks Velocity Hydrograph Data
  • futr NetIQ Identity Manager Future-dated Infotype Cache
  • qmdl Qualcomm Extensible Diagnostic Monitor Log

.def - ESwin Wizard

The DEF data files are related to ESwin. The DEF file is an ESwin Wizard. ESwin is a generic 3D structural design application developed by Procedimientos.

Category:Data files
Magic:- / -

ESwin Wizard related extensions:

  • es ESwin Project

.def - Mugen Character Definitions Data

The DEF game data files are related to Mugen. The DEF file is a Mugen Character Definitions Data. Mugen is a freeware 2D fighting game engine designed by Elecbyte.

Category:Game Data files
Magic:- / -

Mugen Character Definitions Data related extensions:

  • air Mugen Animation Data
  • cmd Mugen Character Commands Data
  • cns Mugen Character States Data
  • sff Mugen Sprite Data
  • snd Mugen Audio Data

.def - Delta Force Weapon Profile Data

The DEF game data files are related to Delta Force. The DEF file is a Delta Force Weapon Profile Data. Delta Force is a tactical first-person shooter computer game by developer and publisher NovaLogic.

Application:Delta Force
Category:Game Data files
Magic:- / -

Delta Force Weapon Profile Data related extensions:

  • wf FIFA 2000 Game Data
  • lv6 Return to Wonderland Game Level Data
  • vis Microsoft Flight Simulator Visibility Data
  • ekv Left 4 Dead Game Data
  • jpp Jigsaw Puzzle Player Data
  • dfs Area 51 Game DFS Data

Be careful.

It is important to understand that the .def file extension is not limited to a particular set of applications. Other programs besides the intended ones can also use the .def extension to create files. This includes potentially harmful programs or malware that may generate .def files for various purposes. Be especially cautious with .def files coming from untrusted or unknown sources.

Can't open a .def file?

When you double-click a file to open it, Windows examines the filename extension. If Windows recognizes the filename extension, it opens the file in the program that is associated with that filename extension. When Windows does not recognize an extension, you receive the following message:

Select an app to open this .def file

To set the .def file association in Windows 11, you can follow these steps

  1. Open the Settings app by clicking on the Start menu and selecting the gear icon.
  2. In the Settings app, click on System and then select Apps from the left-hand side menu.
  3. Scroll down and click on the Default apps option.
  4. Under the Default apps section, you will find various categories such as Email, Web browser, and Music player.
  5. Locate the category that matches the file type you want to associate, such as Photos for image files or Video player for video files.
  6. Click on the current default app listed under the category. A list of available apps will appear.
  7. Choose the app you want to set as the default for that file type. If the desired app is not listed, click on More apps to see additional options or click on Look for an app in the Microsoft Store to search for apps in the Store.
  8. After selecting the app, it will become the default choice for opening files of that type.

It's worth mentioning that you don't always need to set .def file association. Many applications can open .def files without requiring any specific file association to be set.

The .def file extension is often given incorrectly

Based on searches conducted on our site in the past year, we have compiled a list of the most common misspellings. These frequent misspellings can cause confusion and hinder search accuracy. Our goal in providing this list is to help users find the right information more easily and enhance their overall search experience on our website.

These misspellings were the most common in the past year:

cef, d3f, ddf, de, deb, dec, ded, dee, der, det, dev, df, dfe, dff, drf

Is it possible that the filename extension is misspelled?

There is a possibility that the .def filename extension is misspelled. To assist users in identifying potential errors, we provide a list of similar file extensions in our database.

Filename extensions similar to .def:

Operating systems

At, we strive to provide a seamless user experience by ensuring compatibility with a wide range of operating systems. The following is a comprehensive list of the operating systems currently supported by

Windows XP/Vista, Windows 7/8/10, Windows 11, CentOS, Debian GNU/Linux, Ubuntu Linux, FreeBSD, macOS, Mac OS X, iOS, Android

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