wa‧ter‧line /ˈwɔːtəlaɪn $ ˈwɒːtər-, ˈwɑː-/ noun

1. the waterline the level that water reaches on the side of a ship etc:
Two torpedoes struck below the waterline.

2. [singular] the edge of a large area of water, especially the sea, where it joins the land:
As the waterline advanced, the vegetation was swamped.

[TahlilGaran] Dictionary of Contemporary English ▲