| n. | 1. | a mark on a shore line indicating the normal level of the water at high tide, caused by the action of the flowing water; sometimes also used for the mark left at the point of the normal low tide; - called also |
| 2. | the maximum level which some activity has reached and from which it has declined; - called also |
| Noun | 1. | tidemark - indicator consisting of a line at the high-water or low-water limits of the tides |