In the future, it will be enough to press a button to derive an English-Klingon dictionary from a Klingon-English one. At present, computational lexicographers are far from being able to reverse the direction of a dictionary in a way that would be satisfactory. Why? In the course of reversing dictionaries with typologically different languages and with several senses and examples, it has become evident that languages are indeed the most complex structures humans have ever created. Languages differ more than it would be comfortable for software designers. Understanding, describing and structuring these differences in a uniform yet sufficient way has been an everlasting challenge for automatic reversal. The idea of saving tens of years of work by automatic reversal became increasingly tempting since the arrival of computers, and the quest for re-using dictionaries continues. The author has participated in developing a reversible database editor OMBI for the Dutch Language Union''s Committee for Interlingual Resources. The manuscript was created to obtain the postgraduate European Diploma for Lexicography. It presents some solutions for the puzzles in modern lexical database design.