Krom
Krom/kromma (กรม) is a term of Khmer language origin used as a prefix to designate a government department, bureau, or military regiment. Historically, it was used to designate a prince or princess of the blood appointed (ทรงกรม Song Krom) as head of the like. There are five classes of such princes in ascending order: krom muen (กรมหมื่น), krom khun (กรมขุน), krom luang (กรมหลวง), krom phra (กรมพระ), krom phraya (กรมพระยา), and krom kritsadika (กรมกฤษฎีกา). How krom/kromma is used in titles is more fully discussed in "5 feudal titles for prince/princess," below. Note that those who possessed titles ceased to be designated by any personal names. See also the department of Krom Tha, and “Krom Phra Klang”.
Read more about this topic: Thai Royal And Noble Titles