Rex (title) in the context of "Rājan"

The Roman emperor was the ruler and monarchical head of state of the Roman Empire, starting with the granting of the title augustus to Octavian in 27 BC. The title of imperator, originally a military honorific, was usually used alongside caesar, originally a cognomen. When a given Roman is described as becoming emperor in English, it generally reflects his accession as augustus, and later as basileus. Early emperors also used the title princeps ("first one") alongside other Republican titles, notably consul and pontifex maximus.

The legitimacy of an emperor's rule depended on his control of the Roman army and recognition by the Senate; an emperor would normally be proclaimed by his troops, or by the Senate, or both. The first emperors reigned alone; later emperors would sometimes rule with co-emperors to secure the succession or to divide the administration of the empire between them. The office of emperor was thought to be distinct from that of a rex ("king"). Augustus, the first emperor, resolutely refused recognition as a monarch. For the first three hundred years of Roman emperors, efforts were made to portray the emperors as leaders of the Republic, fearing any association with the kings who ruled Rome prior to the Republic.

Rí, or commonly ríg (genitive), is an ancient Gaelic word meaning 'king'. It is used in historical texts referring to the Irish and Scottish kings, and those of similar rank. While the Modern Irish word is exactly the same, in modern Scottish Gaelic it is rìgh, apparently derived from the genitive. Cognates include Gaulish Rix, Latin rex/regis, Spanish rey, French roi, Sanskrit raja, and German Reich.

There were three grades of rí: a ruiri or 'overking' was a major, regional king and superior to a rí túath 'king of tribes' or a rí buiden 'king of bands' either of whom, in turn, were superior to several figures known as rí benn 'king of peaks' or rí túaithe 'king of a tribe'.

The royal we, also known as the majestic plural (Latin: pluralis majestatis) or royal plural, is the use of a plural pronoun (or corresponding plural-inflected verb forms) by one who is a monarch or high office holder to refer to oneself. A more general term for the use of a we, us, or our to refer to oneself is nosism.