What was a denarius during the Roman period?

In the Roman currency system, the denarius was a small silver coin first minted about 211 BC during the Second Punic War. It became the most common coin produced for circulation but was slowly debased in weight and silver content until its replacement by the double denarius, called the antoninianus, early in the 3rd century AD. The word denarius is derived from the Latin dēnī "containing ten", as its value was 10 asses, although in the middle of the 2nd century BC it was recalibrated so that it was now worth sixteen asses or four sestertii. It is the origin of several modern words such as the currency name dinar; it is also the origin for the common noun for money in Italian denaro, in Portuguese dinheiro and in Spanish dinero.