PowerQA has evolved to discussion system by POST-TYPE feature. It is no longer just Q&A system. By this plugin, you can convert all words of your site without changing language file.
Examples of filter settings:
Q&A==Discussions Questions==Threads||questions==threads Question==Thread||question==thread Unanswered==Unreplied||Unanswer==Unreply Answers==Replies||answers==replies Answer==Reply||answer==reply Post types==Thread types||Post type==Thread type Ask==Start||asked==started Start a Thread==Start discussion!||Start a thread==Start discussion!