n. The mark, line, or limit of the rise or height of water, as in a well, a river, the sea, etc.; a water-line; especially, a tide-mark.n. A faintly marked letter, figure, or design in the fabric of paper, that denotes its size or its manufacturer, usually barely noticeable except when the sheet is held against strong light.To mark or stamp with water-lines: as, to water-mark paper; a.water-marked page.To mark, inscribe, or embody in water-lines.