What is to serve the purpose of a watchman by floating properly in its place; -- said of a buoy. To watch over, to be cautiously observant of; to inspect, superintend, and guard called?

watch — (Naut.) To serve the purpose of a watchman by floating properly in its place; -- said of a buoy. To watch over, to be cautiously observant of; to inspect, superintend, and guard. (Webster's 1913.)

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