Cetacea is a term commonly used to refer to whales, dolphins and porpoises, and it is one of the most fascinating orders in the animal kingdom. However, there are several other synonyms for this order, depending on the context. One of the most common synonyms is "Cetartiodactyla," which refers to the evolutionary relationship between whales and hippos. Another synonym is "Mysticete," which specifically refers to baleen whales and their unique feeding mechanism. "Odontoceti" is another synonym used for order Cetacea, and it refers to toothed whales like dolphins and porpoises. Lastly, "Archaeoceti" is a synonym that refers to the extinct whales that lived millions of years ago.