wa‧ter‧mark /ˈwɔːtəmɑːk $ ˈwɒːtərmɑːrk, ˈwɑː-/ noun [countable]

1. a special design put onto paper, especially bank notes, that can only be seen when you hold it up to the light
bear/carry a watermark
The sheet bears the watermark ‘1836’.

2. a special mark contained in electronic documents, pictures, music etc that is used to stop people from copying them:
The card has a digital watermark detectable only by electronic cash dispensers.

3. high watermark especially American English the high watermark of a particular process is its most successful time or achievement Synonym : high point
high watermark of
Reagan’s presidency may prove to have been the high watermark of the US-Israeli alliance.

4. high/low watermark American English a line showing the highest or lowest levels of the sea Synonym : tide-mark British English

[TahlilGaran] Dictionary of Contemporary English ▲