The Interregnum is a term made famous on X and ReadMultiplex by Brian Roemmele. The word itself is defined as a period between two reigns, usually between the death of one king and the crowning of the next. It is often a period of unrest, because there is no uniting power to keep things going smoothly.
But Brian uses this word for a very specific period in human civilization which he refers to as the five thousand days. It is the period where artificial intelligence and robots are starting to drastically change the world, and these S curve movements in technological development combined will disrupt the work environment as we know it, in every aspect of life.
It is the period where robots and AI start taking jobs, but before the positive effects of this takeover have driven manufacturing costs way down, leading to a universal high income situation for everyone.