Aedile : A magistrate who looked after the city of Rome, its corn supply, municipal regulations, and games. The office of aedile came between quaestor and praetor in the cursus honorum (the 'sequence of offices' in the career of a Roman politician).

Augustus :
The title given to the ruling emperor as being the senior ruler of the empire. Abbreviations like AVG could have multiple G's (AVGG) which would indicate a joined rulership of the empire.

Caesar : This title was given to an heir to the throne. (In earlier times Caesar was just a family name but later it got used to describe the heir or junior ruler)

Censor :

Centurio primus pilus : The centurion of the highest centuria (the first centuria of the first cohort)

Comes : A late Roman army commander usually followed by the province in which he was commander for example: Comes Britanniae

Comes Domesticorum : Commander of the household troops, the Emperors personal troops, Commander of the cavalry arm of the imperial bodyguard.

Consul :. The Roman republic was led by two Consuls who were joint heads of the Roman state and commanders-in-chief of the army. They were elected only for one year and thereafter could not be re-elected again for 10 years, in order to prevent any form of tyranny. The main role of consuls was to prepare and propose new laws. Though this required co-operation between the two consuls, as either had the power to veto any proposals by the other. One of the two consuls was usually the Emperor and he could get reelected every year of course .

Consularis : Former consul

Dux : Commander, usually followed by the legion he commanded for example: Dux Moesiae = Commander of the Legion of Moesia

Imperator : Emperor / supreme military commander.  In Republican times the title of  Imperator was given to a general by his troops after an especially great victory. This acclamation was necessary for a general to apply to the Senate for a triumph, after his triumph he would give up the title. After the time of Augustus Imperator was a title restricted solely to the emperor it was used as a praenomen and was taken on accession. It was continued to be used in the Republican sense by the emperor, even if he had not commanded the victorious army in person. In this case the title followed the emperor's name along with the number of times he was acclaimed as such, for example IMP VI ("Imperator six times").

Legatus : A title give to an ambassador send to or by a foreign country but also a title given to an envoy representing another person (sort of being the ambassador of that other person). All legati (plural) had to be sanctioned by the Senate otherwise they could not be legally considered as a Legatus. The title of legatus was given to several different functions.
  1) Ambassadors sent to Rome by foreign nations.
  2) Ambassadors sent from Rome to foreign nations.
  3) Legati who accompanied the Roman generals or Consuls into the field
  4) Legati who accompanied proconsuls and praetors into the provinces. When the proconsul or praetor was absent the legatus would rule in his place with his powers and it happened quite often that a legatus would rule a province for years while his superior was in Rome handling his affairs.

Magister Equitum : A senior roman officer in charge of the cavalry equal in rank to a Praefect.

Magister Equitum Praesentalis : Same as the magister equitum but being close to the emperor. Master of the horse who remained close to the emperor.

Magister Memoriae : An officer whose duty it was to receive the decisions of the emperor and communicate these to the public or the people concerned.

Magister Militum : A senior roman officer in charge of the soldiers of a province. The title was usually followed by the name of the province for example: Magister Militum Per Illyricum. (The master of the soldiers of Illyricum.)

Magister Officiorum : an officer at the imperial court, who had the superintendence of all audiences with the emperor, and extensive jurisdiction over both civil and military officers.

Magister Peditum : A senior roman officer in charge of the foot soldiers equal in rank to a Praefect.

Magister Utriusque Militiae : The senior officer in charge of both military services (foot and horse). The master general or supreme commander of the army.

Patrician : Originally a member of one of the Roman citizen families later a member of the nobility.

Pontifex Maximus : Highest priest of Roman religion and official head of the highest priestly order in the Roman state religion, the pontifical college. This college was made up of fifteen priests, each of whom served a single god or goddess. These priests where also called pontiffs, or pontifices. As the chief administrator of religious affairs the pontifex maximus regulated the conduct of religious ceremonies, consecrated temples and other holy places, and controlled the calendar. He was also keeper of the annals, an annual record of magistrate's names and memorable Roman events. The title pontifex means literally "bridge builder" because they bridged the gap between the world of man and the world of the gods. During the time of the empire, and until Christianity became firmly established, the emperor was designated pontifex maximus (emperor Gratian was the first Christian emperor to refuse the title). After the supremacy of Christianity, the popes assumed this title.

Praefect (Praefectus) : A title used in the Roman empire to refer to various high ranking officials who governed territories or in some way represented Roman authority, as overseer, civil or military officer or tax collector. This was usually indicated by a secondary title for example:

Praetorian Praefect : the leader of the Praetorian Guard , under Diocletian this became an administrative job they were expert jurists and administrators overseeing imperial administration.
Praefectus Castrorum : the commander of the camp of a roman legion
Praefectus Vigilum : the commander of the nightwatch

Praefectus Urbis : the administrative governor of Rome

Praetor : A Roman magistrate, responsible for the administration of justice, they served as the supreme civil judges for legal cases. They also acted as a deputies to the consuls, in particular regarding the administration of the provinces. A praetorship was also part of the cursus honorum (the 'sequence of offices' in the career of a Roman politician).

Proconsul :
A provincial governor. He was in charge of the army, of justice, and of administration in his province and could not be prosecuted for maladministration until his office expired.

Procurator : A title for employees of the Roman emperor who were engaged in the administration of the empire. Some procurators governed small provinces, while others served as agents of the emperor in larger provinces. These procurators performed a variety of duties ranging from tax collection to the administration of imperial estates.

Protector : A bodyguard and in the late roman army a staff officer.

Protector domesticus : A bodyguard in the household troops of the Emperor.

Quaestor : A quaestor handled finances in Rome or the provinces and held a seat in the Senate. A quaestorship was also part of the cursus honorum (the 'sequence of offices' in the career of a Roman politician).

Quaestor sacri palatii
: The highest legal officer in the empire responsible for the judicial organization and the passing of laws

Rector Orbis : This title means ruler or master of the world.

Rector Orientis :
This title means ruler or master of the East.

Scutarius : Literally translated "Shieldbearer" in the army it was a guardsman who's primary weapon was a large shield.

Senator : There were 600 senators (from the time of Augustus onward) who were the governamental body of Rome and extremely influential. They controlled the public finances decided on foreign affairs and assigned military and provincial commands. From the time of Augustus onward the powers of the senate declined rapidly because most emperors had the backing of the military and no longer needed the senate and the senate eventually became much more a body of prestige then of power.

Tribune : A senior military officer usual followed by a secondary title for example :

Tribunus cohortis: commander of an auxiliary unit.

Tribunica Potestas : This title means Tribunician Powers, a patrician could by law never be a peoples tribune but starting with Augustus all the powers of the peoples tribune could be given to the emperor or caesar with the title Tribunica Potestas without him actually holding the office. These powers entailed, the absolute right of veto of any law or decision and the authority to convene the Senate. It also granted the holder sacrosanctity meaning he couldn't be prosecuted or harmed while holding the title, and it allowed the holder of the title the right to exercise capital punishment on anyone who hindered him in the performance of his duties. This title was renewed every year and on coins this is indicated by putting the number of times the title had been renewed behind the title, for example TRI POT III means that the title has been renewed for the third time making it an excellent way of dating coins.

Vicarius : A lieutenant or an administrative ruler of one of the twelve dioces created in the time of Diocletian for example : vicarius Africae