Originally, during the Roman Republic, the word maiestas was the legal term for the supreme status and dignity of the state, to be respected above everything else.
This was crucially defined by the existence of a specific case, called laesa maiestas (in later French and English law, lèse-majesté), consisting of the violation of this supreme status.
[1] After the fall of the Holy Roman Empire, Majesty was used to describe a monarch of the very highest rank— it was generally applied to God.
In monarchies that do not follow the European tradition, monarchs may be called Majesty whether or not they formally bear the title of King or Queen, as is the case in certain countries and amongst certain peoples in Africa and Asia.
In Europe, the monarchs of Denmark, Norway, Sweden, the United Kingdom, Spain, the Netherlands and Belgium use the style.
By contrast, the heads of state of Liechtenstein and Monaco, being principalities, use the inferior style of Serene Highness.
Moreover, while Andorra is formally a monarchy, its Co-Princes – the bishop of Urgell (appointed by the Pope) and President of France – use the republican and non-royal style of Excellency.
In the United Kingdom, several derivatives of Majesty have been or are used, either to distinguish the British sovereign from continental kings and queens or as further exalted forms of address for the monarch in official documents or the most formal situations.
Britannic Majesty is the style used for the monarch and the crown in diplomacy, the law of nations, and international relations.
The standard is as follows: BE IT ENACTED by the King's [Queen's] most Excellent Majesty, by and with the advice and consent of the Lords Spiritual and Temporal, and Commons, in this present Parliament assembled, and by the authority of the same, as follows:Wives of Kings are entitled to the style of Her Majesty (such as Queen Camilla).
This designation stems from the concept of Devaraja or God-King (เทวราชา), where the Thai King is considered a part of Vishnu, one of the highest gods in Hinduism.
The names of Thai kings also signify divinity, such as Ramathibodi meaning Rama the sovereign, Naresuan signifying God in human form, and Ramesuan a combination of Rama and Ishvara[5] There is further evidence of similar uses, such as Somdet Phra Puttha Chao Yu Hua (สมเด็จพระพุทธเจ้าอยู่หัว), implying that the king holds the status of a Bodhisattva destined to attain enlightenment and become a Buddha in the future.