waterline [wôt′ərlīn΄]n.1. the line to which the surface of the water comes on the side of a ship or boat2. any of several lines parallel to this, marked at various heights on the hull of a ship, indicating the various degrees of submergence when the ship is fully or partly loaded, or unloaded, and on an even keel☆ 3. a pipe, tube, or other line connected to a source of water4. WATERMARK (sense 1)
* * *water line or wa·ter·line (wôʹtər-līn', wŏtʹər-) n.1.a. The line on the hull of a ship to which the surface of the water rises.b. Any of several lines parallel to this line, marked on the hull of a ship, and indicating the depth to which the ship sinks under various loads.2. A line or stain, as one left on a seawall, indicating the height to which water has risen or may rise; a watermark.
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