1(in ancient Rome) a group of three men holding power, in particular ( the First Triumvirate) the unofficial coalition of Julius Caesar, Pompey, and Crassus in 60 bc and ( the Second Triumvirate) a coalition formed by Antony, Lepidus, and Octavian in 43 bc.
a group of three powerful or notable people or things:a triumvirate of three executive vice presidents
2the office of triumvir in ancient Rome.
late 16th century: from Latin triumviratus, from triumvir(see triumvir)
triumvirate in other Oxford dictionaries
Definition of triumvirate in the US English dictionary