The term 'PIRATE's Domain' can be broken down into two crossword solutions: SEA (3 letters) and OPENSEAS (8 letters). The term 'SEA' is an acronym for the body of salt water that covers most of the Earth's surface. It is also known as the ocean, and it is home to many different species of marine life. The term 'OPENSEAS' refers to the open waters of the SEA, which are not subject to any particular country's jurisdiction. This area is often used by pirates to hide from authorities and conduct their illegal activities.