A line showing where the water has been, usually a line separating dry land and wet areas; a watermark or tidemark.
A line formed by the surface of the water on the hull of a ship when she is afloat; any of a series of short lines marked on the hull to show where the waterline would be under different loadings.
A horizontal line indicating the shape of an airfoil.
The inner rim of the eyelid, just behind the lash line; primarily used in reference to the application of eyeliner.
A mark indicating the level to which water has risen.
A translucent design impressed on the surface of paper and visible when the paper is held to the light.
A logo superimposed on a digital image, a television broadcast, etc.
A value stored in a datafile to ensure its integrity, so that if the file's contents are changed then the watermark will no longer match the contents.
To mark paper with a watermark.
To mark a datafile with a digital watermark.