Here are the answers based on your descriptions:
- Basic unit of the Roman army, consisting of 4,500 to 5,000 heavily armed soldiers: legion
- Open area in a Roman city filled with public buildings, temples, and markets: forum
- Title used by Roman emperors meaning venerable or greatly honored person: augustus
- Channel that moves water over a long distance: aqueduct
- Garment that adult men wore wrapped around their bodies as a symbol of Roman citizenship: toga
- Form of government in which citizens have the right to vote and elect officials: republic
- State containing several countries or territories: empire
- Period of stability in the Roman empire: pax romana
Let me know if you need any more assistance!