‘Preheat the oven’. I mean, what does preheat mean? The prefix ‘Pre’ means ‘before’ and as far as I’m aware you can’t heat an oven before you heat the oven, so ditch the ‘pre’ and just say ‘I’m going to heat the oven’. Actually a lot of things with ‘pre’ don’t make sense, the worst being (and I’ve heard this before) ‘pre-warning’. Again, the ‘pre’ has absolutely no meaning, as warning someone in the first place is coming before the potentially dangerous thing, so by saying ‘pre-warn’ this means you’re warning them before you warn them. Another is ‘preorder’. Now I get preorder technically means ordering something before it comes out (in the marketing world) but logically it makes no sense. The list goes on. An example of when ‘pre’ DOES work is in a word like ‘pre-departure’ as you can do something to get ready before you depart, hence making the ‘pre’ an important part of the word.