n
1 manufacturer's design in some types of paper, which can be seen when the paper is held against the light （某些种类的纸上印制的）水印.
2 mark that shows how high water (eg the tide or a river) has risen or how low it has fallen 水位标志（如潮水或河流的）.

n[C]
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'.
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 to electronic cash dispensers.
high watermark
especially AmE the high watermark of a particular process is its most successful time or achievement
= high pointhigh watermark of
　Reagan's presidency may prove to have been the high watermark of the US-Israeli alliance.
high/low watermark
AmE a line showing the highest or lowest levels of the sea
British Equivalent: tide-mark