Quote from jeb9999:
That is not slippage. Slippage is: Price erosion between a Quoted Price and an Execution.
You are not going to get a 1000 lot limit order filled in ES without the price going through your limit. It is totally unrealistic to assume that the market will be generous enough to fill your order and then go in your direction.
Like has been suggested above, slippage is a term often used to describe the expected price versus the one you get.
It would probably be more accurate to describe the situation I outlined as "synthetic slippage" because the effects are exactly the same. Thus it could easily be described as the synthetic equivalent of slippage.