If it is frozen, then I'm sorry you have to force quit it. It is not going to unfreeze itself. There is no other way to unfreeze it and no way to save the document now. But if the Auto recovery functions is turned on which is very likely as default, then Word will recover and open the document automatically next time you open Word. Press Command, Option and Esc keys and this will bring Force Quit. Select Word, Force quit and open it. Does it open the document ?
If not, then check the Auto recovery folder. In Finder, click on Go menu and select Home. Then open Documents folder. Open Microsoft folder and open Auto recovery folder. If you see any files there, then rename the files (to rename, select the file and press return key to bring the selection on name) and add .docx or .doc at the end ofthe file name and then open it with Word. Do you see your document ?
There is also one more place to check. If you are lucky, you may find a backup in here. In Finder, hold down Option key, click on Go menu and select Library. From Library, Open Application Support folder, open Microsoft, open Office folder. Open Office Auto recovery folder and do you see them there ?
If not, then it is too late now. There is no other way to get it back if it is not in that folder.I know you are looking for a way to get it back, but the fact is, it is gone.
If you have any questions or would like any additional information, please don't hesitate to ask. Let me know the results please.