tidemark /ˈtaɪdˌmɑɚk/ noun plural tidemarks
plural tidemarks
Learner's definition of TIDEMARK
[count]
1
chiefly British : a mark on the beach that shows how far the water came in toward the shore when the tide was high(潮水在海岸上留下的最高)潮痕
2
British, informal : a mark left by dirty water in a bathtub(浴缸内污水留下的)垢痕