1. a conspicuous object on land that serves as a guide for navigation at sea
Usage: nautical
2. a buoy, lighthouse, or other marker placed in or near water to guide ships
Usage: nautical

Examples

• The lighthouse served as an important seamark for ships entering the harbor.
• Sailors relied on the church tower as a seamark when approaching the coast.
• The red buoy was placed as a seamark to warn of shallow water.
• Ancient mariners used prominent hills and cliffs as seamarks for navigation.
• The harbor master installed new seamarks to improve shipping safety.
• Without GPS, the crew depended on traditional seamarks to find their way.