1. one of three people who share power or authority equally
Usage: historical
2. specifically, one of three Roman magistrates who jointly administered the government
Usage: historical; Roman history

Examples

• Julius Caesar was a triumvir in the First Triumvirate with Pompey and Crassus.
• The three triumvirs divided the Roman territories among themselves.
• Mark Antony served as a triumvir in the Second Triumvirate.
• Each triumvir controlled different aspects of the government.
• The triumvirs agreed to rule jointly for five years.
• Octavian was the youngest of the three triumvirs.
• The triumvirate system allowed three leaders to share power equally.