The waterline of a ship.
Of a route that follows a riverbank or shoreline.
An instrument to show the level by means of the surface of water in a trough, or in upright tubes connected by a pipe.
The level of a body of water, especially when measured above a datum line.
The level of the water table below ground.
A line formed by the surface of the water on the hull of a ship when she is afloat; any of a series of short lines marked on the hull to show where the waterline would be under different loadings.
A line showing where the water has been, usually a line separating dry land and wet areas; a watermark or tidemark.
A horizontal line indicating the shape of an airfoil.
The inner rim of the eyelid, just behind the lash line; primarily used in reference to the application of eyeliner.