tidemark

1 ENTRIES FOUND:
tidemark /ˈtaɪdˌmɑɚk/ noun
plural tidemarks
tidemark
/ˈtaɪdˌmɑɚk/
noun
plural tidemarks
Britannica Dictionary 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
2 
British, informal : a mark left by dirty water in a bathtub