DEFN File Extension

TIP: Run a Free Scan for .DEFN File Errors.

Files with the extension .DEFN are known as "Microsoft Dictionary".

This file format was added to our database by a visitor to this site, but no additional information was provided.

We have yet to investigate the DEFN file extension any further, or there was simply not enough information available at the time to report accurately on the format. If you know how to open DEFN files or even how to convert or edit them, please use the form below.

However, it is possible that other file formats exist which also use the DEFN extension, so please let us know if you do not think the DEFN extension matches the file format you are looking for.

How to Open .DEFN (Microsoft Dictionary) files