Rear car is a term used to describe the last car in a train or convoy. There are several synonyms that can be used in place of the rear car. The most common one is "caboose," which is an American term that has been used since the 1800s. Another synonym is "tail car," which is a more descriptive term and refers to the car at the tail end of the train. Other synonyms include "end car," "guard car," "conductor's car", and "observation car." All of these terms can be used interchangeably with "rear car," depending on the context and the speaker's preference.