Palace cars are luxurious train cars that were commonly used in the 19th and early 20th centuries. These cars were designed to transport wealthy passengers in comfort and style, with amenities like plush seats, sleeping compartments, and dining areas. Synonyms for the term "palace car" include "royal car," "parlor car," and "saloon car." In addition, "luxury car" and "first-class car" are also used to describe this type of train car. These terms all refer to the same idea of a train car that is designed to provide a high level of comfort and luxury to its passengers.