Indictio is a Latin term that refers to a system of counting years used in the Roman Empire during the late antiquity period. It can be translated as "indiction" in English. The concept of indiction is derived from the Greek word "ένδεκα" (endēka), meaning "eleven."
In essence, indiction was a cycle of 15 years that served as a means of organizing various administrative and fiscal obligations within the Roman Empire. It was introduced by the Emperor Constantine the Great in the 4th century CE, with the purpose of assessing and collecting taxes more effectively. The indiction cycle allowed for better planning and regularity in the assessment and distribution of taxation.
Each indiction period was numbered consecutively, starting with the first year of Constantine's reign. Therefore, the first indiction was referred to as "indictio prima," the second as "indictio secunda," and so on. The cycle continued until the fifteenth year, after which a new cycle would commence with the next indiction.
Apart from its fiscal and administrative functions, indiction also served as a dating method in official documents and historical accounts during that time. It provided a common reference point for dating specific occurrences and was especially relevant in legal, ecclesiastical, and diplomatic contexts. The indiction number, together with the year of a reign or another dating system, offered a clear chronological framework.
Although the indiction system gradually fell out of use during the medieval period, its influence can still be seen in historical records and documents from the Roman Empire. Nowadays, the term indiction is predominantly used in academic and historical discussions to refer to this specific Roman chronological system.
