How do I combine user defined dictionaries into one?

When I created a user defined dictionary, I assumed, perhaps erroneously, it would be available to all my creations even if those creations were in different folders. I would like to reference one User Defined Dictionary with all my previously corrected words from many different folders. So where is the User Defined Dictionary kept? (Please name path and file in answer.) And how can I combine them into one file for future reference? TYVM. William

Please advise your LO version and operating system name and version, as the answer will depend.