The imperial nomenclature developed round the names of the first holders of the position, but not every name included every element. Some elements (in a likely sequence) were: Imperator (originally a title awarded under the Roman Republic to a magistrate in the field); Caesar (of course originally a surname of Julius Caesar; then it became a hereditary title); next the personal names of the current emperor (for example Titus Flavius Vespasianus, Vespasian), followed by the title Augustus (both Caesar and Augustus helped the ruling emperor to legitimize his power by referring to his 'predecessors'). It was quite normal for an emperor to adopt some of the family names of his predecessor, e.g. Antoninus Pius' personal names after adoption became Hadrianus Antoninus (referring to his adoptive-father, Hadrian). After their death some emperors were deified, and were accorded the title divus. If the successor was the son of an emperor who had been deified, he could be termed divi filius (son of a god). But there are also various extra titles...
A briljant example of Imperial nomenclature is an inscription at a statuebase from Ostia, in honour of the emperor Sepitmius Severus, AD 196 (now in the Corile della Pigna, Vatican Museums):
Imperatori Caesari Marci Antonini Pii Germanici Samatici filio divi Commodi fratri divi Antonini Pii nepoti divi Hadriani pronepoti divi Traiani Parthici abnepoti divi Nervae adnepoti Lucio Septimio Severo Pio Pertinaci Augusto Arabico Adiabenico pontifici maximo tribunicia potestate IIII imperatori VIII consuli II patri patriae.
Meaning:
To the emperor Caesar, son of the deified Marcus Antoninus Pius, victor over the Germans and the Sarmatians, brother of the deified Commodus, grandson of the deified Antoninus Pius, great-grandson of the deified Hadrian, great-great-grandson of the deified Trajan, victor over the Parthians, great-great-great-grandson of the deified Nerva, Lucius Septimius Severus Pius Pertinax Augustus, victor over the Arabs and the Mesopotamians, chief priest, holder of the tribunician power four times, saluted Imperator eight times, consul twice, father of this country.