Point 3. Royal Words
The Thai language possesses an elaborate vocabulary to be used when speaking of or to the king and other high-ranking members of the royal family. The practical purposes for which this book is intended make it unnecessary for you to learn these words, but it is important that you know there are such terms. By way of example, you should note the instances taken from the Basic Sentences of this unit.
English ภาษาไทย
The king is still the head of the country. พระมหากษัตริย์ก็ยังคงทรงเป็นประมุขของประเทศ
The king uses the sovereign power of the constitution. พระมหากษัตริย์ทรงใช้อำนาจอธิปไตยแห่งรัฐธรรมนูญ

Here we find that there is a prefix soN- which is placed before verbs which describe the actions of the king.