Savageduck
We are descending into silliness here. A reversible process is one where any changes made in the execution of that process can be reversed to revert to the original state

Floyd L. Davidson
You have long since ceased anything not silly. But using your own definitions of very technical terms just leads to farther down the same path. Your definition is trivial, and not valid in a technical discussion.

Reversiblility is not equivalent to revertability.

And undo function (linear or not) reverts. That is it goes back to a previous state.

A "reversible function" incrementally moves forward, or backward, in granular steps that are necessarily small compared to the potential range.

An excellent definition for the difference between a reversible function and a non-reversible function is that in an isolated system entropy change will be greater than 0 with a non-reversible process, and will be 0 with a reversible process.

That means there is one original state, and one current state that derives from a specific process that cannot produce any other state; and if 1) the process is reversible there is only one possible state if the process moves backwards, while 2) there are multiple different possible states if an irrevsible process moves backwards.