Porpoises are aquatic mammals that belong to the cetacean family, which also includes whales and dolphins. They are known for their streamlined body, small size, and playful behavior. There are several synonyms for the word "porpoise," which can be used interchangeably depending on the context of the sentence. These include sea pig, mereswine, and haliaetus. Other synonyms for porpoises include dolphins, which are closely related to porpoises, and orcas, which are technically classified as a type of dolphin but are commonly referred to as killer whales. Overall, porpoises and their synonyms are fascinating animals that are beloved by many people around the world.