When you add a word to the dictionary using spell checker it will create or add to the orion.dct file in the same path from which you are launching oriondesktop.exe.  This would be O:\orion\orwin in the most common scenario but could also be the local C: in some citrix environments.  If you are getting errors when trying to add a word it could be that the User has lost rights to modify that file. 

To check the User rights browse to the folder and right click on the orion.dct file.  Now go to the Security Tab.  Here you could have a general name of “users” and give it full control.  You could also see your network login name here and would need to give full control to that as well.  The shortcut, if your IT’s security will allow it, is to click edit, add, type in everyone in the “Enter the object names to select” box and press ok.  Check the full control box for the “everyone” user now. 

Press apply and hit ok.  You should now be able to add a word to the dictionary.