If you believe definitions constituent to a hypothesis are ever orthogonal to it, this would be a mark in the ledger in favor of there being an overall decline in reasoning ability. By this logic, I can simply say “x is a responsible for a decline in y, as evident by the comparable measure of z” without ever having to define any of those variables and always be correct. Does that seem rational or useful to you?

Look, I can understand what you say, and you can understand me, without us defining all or any of the words we use. We don't need a definition of definition. We can know what things mean without having a definition of "knowledge" or "meaning".

That more abstract claim was never what is at dispute. The OP’s claim instead requires clear and consistent definitions of the categories involved in order to be a falsifiable hypothesis, which were not provided. Your defense of this is apparently that because it also exists on the low end of the spectrum of some basic intelligibility that also makes it a hypothesis, which is, again, also incorrect. It’s a supposition that never rises to this level because it lacks these aspects.