Why is it called "de-watering"?

Some appellations have been established. For example, an apple is called an apple, and you are your son's mother, not his father. You can tell your son it's a code name. Everyone calls water water. Of course, you can call it water and oil, but how can you communicate with others?

Give everything a fixed name for better expression and communication. Just tell him that water is water. Everyone calls this liquid water, so water becomes water.