What is the inverse of iota?

Could you please clarify for me what the inverse of iota actually represents? I'm somewhat familiar with cryptography and the usage of Greek letters in various mathematical and scientific contexts, but the concept of an inverse in this specific instance isn't entirely clear to me. Is it related to some specific property of iota in cryptography or is it a more general mathematical concept? Could you elaborate on its definition and possibly provide an example or two to illustrate its meaning? I'm really curious to understand this concept better.