📘 English Definition（英文释义）
- Any one of certain lines of a vessel, model, or plan,
- parallel with the surface of the water at various heights from the
- keel.
- Any one of several lines marked upon the outside of a
- vessel, corresponding with the surface of the water when she is afloat
- on an even keel. The lowest line indicates the vessel's proper
- submergence when not loaded, and is called the light water line; the
- highest, called the load water line, indicates her proper submergence
- when loaded.