I was looking for free dictionary data in my local language to use in a proprietary application that I'm working on, I found such data but in a GPL 3 licensed program on SourceForge, the data is available in XML files that is distributed along with the program. Generally I know how to deal with apps and libraries covered by GPL... but data, that's new to me.
Is it possible to use this GPL-licensed data in my proprietary application?
I guess you should search for a FreeBSD licenced solution.
It's difficult to find one, I know.
GPL licence applies to all kinds of things: programs and libraries are only a couple of cases. So the data in XML form are treated in exactly the same way as source code of a GPL-licensed program. Therefore, you can't use them in your proprietarry application.
However, you may try to contact the copyright owner and negotiate for re-licesing the data under proprietary license specially for you. Maybe you can persuade him without fee, who knows?