According to the etymology given in my MS Encarta dictionary: . the word episode is: . "... Late 17th century. From Greek epeisodion ‘addition’, a form of epeisodios ‘coming in besides’, from eisodos ‘coming in’, from hodos ‘road’.] ..."
Best wishes - Majikthise. .
I am assuming Greek. It has been around since literature like One thousand and One Nights (arabian nights)