In his book Rationality, Steven Pinker says that the way we mentality categorize things is not by a strict definition, but with a number of properties that make things more it less like the category. So it’s like, if it has green vegetables, it’s more likely to be a salad, if it’s served hot is less likely, etc. This avoids issues like this where trying to strictly define things leads to absurd results. I think he even used salad as an example in the book.