ses·terce 
(sĕstûrs′)
(sĕstûrs′)n.
A silver or bronze coin of ancient Rome equivalent to one fourth of a denarius.
[Latin sēstertius, a coin worth two and a half asses : sēmis, half; see sēmi- in the Appendix of Indo-European roots + tertius, third; see trei- in the Appendix of Indo-European roots.]