Editorship is the top job at a newspaper or a magazine: you are the editor, the person who decides what goes in and who is in charge of the writers. People also use it for the stretch of time someone held that job — 'during her editorship' means 'in the years when she was the editor.' It is a rather formal word. You meet it in news, in books about journalism, and in polite notices when someone takes the job or leaves it. Though actually, it is not only paper and ink; a journal, a website, even a radio programme can have an editorship. What it does not mean is the everyday work of fixing commas and cutting lines. That is just editing. Editorship names the position, or the period, not the scissors.