AbiWord is free word processor for Windows, macOS (Mac OS X) and Linux and uses unique .abw files to store documents saved in the program. These files typicaly cannot be opened in other word processors so a lot of users try to convert abw to doc or any other similar document format.
As far as we know, this can only be done using AbiWord itself and since you can download the program for free, it should be pretty easy to get your .abw documents in .doc format simply by using the File ► Save as.. function.
Some users have also reported to us that the KWord word processor for Linux also supports abw documents, so that's another viable alternative for Linux users to perform abw to doc conversion.
Updated: July 27, 2016