A flamen was a priest of the ancient Roman religion who was assigned to one of fifteen deities with official cults during the Roman Republic. The most important three were the flamines maiores (or "major priests"), who served the important Roman gods Jupiter, Mars, and Quirinus. The remaining twelve were the flamines minores ("lesser priests"). Two of the minores cultivated deities whose names are now unknown; among the others are deities about whom little is known other than the name. During the Imperial era, the cult of a deified emperor (divus) also had a flamen.
The fifteen Republican flamens were members of the Pontifical College, which administered state-sponsored religion. When the office of flamen was vacant, a pontifex could serve as a temporary replacement, although only the Pontifex Maximus is known to have substituted for the Flamen Dialis, one of the flamines maiores.
By the time of the religious reformation of Augustus, the origins and functions of many of the long-neglected gods resident in Rome was confusing even to the Romans themselves. The obscurity of some of the deities assigned a flamen (for example Falacer, Palatua, Quirinus and Volturnus) suggests that the office dated back to Archaic Rome. Many scholars[who?] assume that the flamines existed at least from the time of the early Roman kings, before the establishment of the Republic. The Romans themselves credited the foundation of the priesthood to Numa Pompilius, the second king of Rome. According to Livy, Numa created the offices of the three flamines maiores and assigned them each a fine robe of office and a curule chair. The flamines were circumscribed by many taboos.
The origin of the word flamen is as obscure as are some of the assigned gods. Sophus Bugge suggested in 1879 that flamen is from an older *fl?dmen and related to the Germanic blót. Both would be derived from a Proto-Indo-European word *bhl?d(s)men.Indo-Europeanist Georges Dumézil attempted to link it to the Sanskrit word brahman. This etymology is still controversial.
The official costume of a flamen, allegedly of great antiquity, was a hat called an apex and a heavy cloak called a laena. The laena was a double-thick wool cloak with a fringed edge, and was worn over the flamen's toga with a clasp to hold it around his throat. The apex was a leather skull-cap with a chin-strap and a point of olive wood on its top, like a spindle, with a little fluff of wool at the base of the spindle.
The three flamines maiores were required to be patricians:
A fourth flamen maior was dedicated to Julius Caesar as a divinity (divus) of the Roman state. Thereafter, any deceased emperor could be made divus by vote of the senate and consent of his successor, and as a divus he would be served by a flamen. The flamen's role in relation to living emperors is uncertain; no living emperor is known to have received official divine worship; see Imperial cult.
A flamen could also be represented by a proflamen, or by a member without that title who could act as a substitute for the flamen (qui vice flaminis fungebatur).
There were two other flamines minores during the Republican period, but the names of the deities they cultivated are unknown. The flamines minores seem mostly connected to agriculture or local cults. The change to an urban way of life may explain why these deities lost their importance or fell into oblivion.
The Floralis and Pomonalis are not recorded in calendars as their festivals were moveable. Some information exists for the ritual roles of the Portunalis in connection with the cult of the god Quirinus and Volcanalis in connexion with the cult of the goddess Maia on the Kalends of May. Also preserved is the list of deities invoked by the flamen Cerialis when he officiated at sacrifices to the goddesses Ceres and Tellus.
Scholars disagree about some differences among flamines maiores and minores. Some maintain the difference was not substantial. Others, among them Dumézil, believe that inherent differences lay in the right of the auspicia maiora and the ritual of inauguration that concerned only the maiores by birth as farreati, that is, as children of parents married through the ritual of confarreatio, which was the form of marriage in turn required for maiores. The maiores also had the privilege of having calatores, assistants who carried out day-to-day business. The difference would thus be akin to that between magistracies with imperium and those with potestas only.