Is it ensure, insure, or assure?
ancient Roman public contractor, who erected or maintained public buildings, supplied armies overseas, or collected certain taxes, particularly those supplying fluctuating amounts of revenue to the state (e.g., tithes and customs). The system for letting contracts was well established by the 3rd century BC: at Rome they were normally let for five years at auctions by the censor; in Sicily they were annually let by the governor. In order to have sufficient security, publicans formed partnerships and companies (societates publicanorum) under officials known as magisters, at Rome. The publicans, primarily members of the equestrian order (equites), gained significant power in the provinces and in Rome when equestrians became jurors in the court of extortion, which investigated the activities of provincial governors (122 BC). Under the early empire (after 27 BC) the publicans' business was curtailed; they were more tightly controlled, and the government forced them to accept unprofitable contracts. The system fell into disuse in the late empire.