Yes and no. The word stems from there, but an episteme is how Foucault describes the evolution of history and science. Rather than it be a linear trajectory with clear and distinct decisions being the indicators of success, progress, etc. (i.e. because Adolph went mad, and because Churchill did X, Germany lost the war), Foucault would say that, well, there's more to it. Surely those had their influences, but who's to say that economical or geographical factors didn't already determine hos defeat in the first place, regardless of his sanity or cleverness of the Brit? Same foes for science. Foucault would agree that science today would look similar to how it is now even if Darwin, Freud, or Einstein had never existed. He has his reasons for believing this, and I think a lot of it has to do with how he views power and its influence on the making of history, but thats about the extent of my knowledge.