Vestmental is an uncommon term that refers to something related to a vestment or a religious robe. There are several synonyms for this word that can be used in its place. One alternative is the word "vestmentary," which similarly refers to something related to religious vestments. Another possibility is the word "robed," which is a more general term that can be used to describe someone who is wearing any type of robe or gown. The words "apparelled" and "clad" can also be used as synonyms for vestmental, as they both refer to the clothing that someone is wearing. Ultimately, the choice of synonym will depend on the context in which the word is being used.