The term “dark pattern” refers to user interface design patterns. That’s where the “pattern” bit comes from. There was already a term for anti-pattern which referred to mistakes. I wanted a term that had a Machiavellian tone to it, so I chose “dark” (Star Wars, Harry Potter, why not?).

I’m not quite sure why this term proved to be so popular. I think it is helpful to have a term that is a little vague though, as it can be a lot of work to pin down whether something is truly deceptive with an outcome of harm - or just an annoying attempt to nudge.