1) Coin of ancient Rome 
The quinarius was a small silver Roman coin valued at half a denarius. The quinarius was struck for a few years, along with the silver sestertius, following the introduction of the denarius in 211 BC. At this time the quinarius was valued at 5 asses. The coin was reintroduced in 101 BC as a replacement for the victoriatus, this time valued at 8 as...
(from the article `coin`) ...currency; together with its fractions, it was now always struck and not cast. The value of the denarius in terms of bronze was altered, being ...
A half-Denarius coin. The plural is 'quinarii.'
a denomination of ancient Roman coinage, issued in silver or gold at various times and undergoing many changes of value.