What does "sesterce" mean?

Sesterce: A Roman coin or denomination of money, in value the fourth part of a denarius, and originally containing two asses and a half, afterward four asses, -- equal to about two pence sterling, or four cents. Note: The sestertium was equivalent to one thousand sesterces, equal to £8 17s 1d. sterling, or about $43, before the reign of Augustus. After his reign its value was about £7 16s. 3d. sterling. The sesterce was originally coined only in silver, but later both in silver and brass.