Definition from Wiktionary, the free dictionary
From Late Latin pentarchia, from Ancient Greek πενταρχία (pentarkhía), from πεντα- (penta-, “penta-: five”) + -αρχία (-arkhía, “-archy: rule”), perhaps via Middle French pentarchie. Equivalent to pent- + -archy.
pentarchy (plural pentarchies)
- (politics) Government by five persons.
- A governing body consisting of five persons.
- A federation of five nations, each under its own government or ruler.