A more thorough explanation:

Mare (pronounced mair-ee or mahr-ee) is a Latin word that means "the sea." It can also refer to a body of navigable water that is under the control of a particular nation or open to all nations.

• Mare clausum: This Latin term means "closed sea." It refers to a body of water that is under the jurisdiction of a particular nation and is closed to other nations. For example, the Black Sea is a mare clausum because it is bordered by several countries, and its waters are not open to all nations.
• Mare liberum: This Latin term means "free sea." It refers to a body of water that is open to all nations. For example, the Atlantic Ocean is a mare liberum because it is not controlled by any one nation, and its waters are open to all nations for trade and travel.

These examples illustrate how the term "mare" can be used to describe different types of bodies of water, depending on whether they are open or closed to other nations. Mare clausum and mare liberum are both important concepts in international law and have been the subject of many historical disputes.