watermark

A translucent design impressed on the surface of paper and visible when the paper is held to the light.

(by extension) 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.

A mark indicating the level to which water has risen.

To mark paper with a watermark.

To mark a datafile with a digital watermark.