pöördvormideks

Could you clarify the intended meaning and field of the term "pöördvormideks"? It appears to be Estonian for "as inverse/reverse forms," but without context it could refer to linguistics (inverse forms in grammar), mathematics (inverse forms or operations), or a different area. If you specify the domain and desired meaning, I can write a precise, neutral wiki-style article under 300 words. If you want a fictional or general overview, I can provide that as well.