A boat motor is an essential part of any watercraft that helps to move it forward through the water. However, there are several other synonyms for boat motor that can be used interchangeably. Some of the most commonly used include outboard motor, marine engine, and boat engine. Outboard motor refers to a motor that is mounted on the outside of the boat and is tilted up for easy transportation. Marine engine is a more general term that describes any engine used in a watercraft. Boat engine is another commonly used synonym that encompasses all types of engines used in boats, including inboard engines.