Afterparts are the portions located at the back of something, such as a boat or an aircraft. There are several synonyms that can be used in place of the word afterparts, which can vary depending on the context. For example, in a nautical setting, the term stern or aft might be used. Additionally, the words tail or rear are often used as synonyms for afterparts in an aircraft context. In some cases, the words back or end can also be used, especially if the context does not specifically refer to a vehicle or vessel. Overall, there are many ways to describe the afterparts of something, depending on the situation and the terminology being used.