My wife recently purchased a Nokia Lumina 920 Windows 8 phone. And while she can still handily beat me at Words With Friends, she now has a bit of a handicap. It seems as though Words With Friends on her Windows 8 phone won't let her play quite a few words that start with the letter Z.
Shown below are screen shots of words the Windows 8 version of the app won't let her play. You can see at the top of each of the screen shots that it says "Sorry ____ is not an acceptable word". All of these words work on the iPhone version of the app.
Its a strange bug and has been a problem for her for about 3 months now. I doubt its limited to just her phone make/model. More likely its a bug on the entire Windows 8 mobile platform build of the app.
Its surprising that maker Zynga hasn't fixed the Words With Friends app on Windows 8.
So far this is the list of words that have been deemed as "not an accetpable word" by her Words With Friends app on Windows 8 phone.