1. A state in which the supreme power rests in the body of citizens entitled to vote and is exercised by representatives chosen directly or indirectly by them.
2. Any body of people viewed as a commonwealth.
3. A state in which the head of government is not a monarch or other hereditary head of state.
4. When capitalized, any of the five periods of republican government in France; for example: First Republic, Second Republic, Third Republic, Fourth Republic, Fifth Republic.
5. A philosophical dialogue (4th century B.C.) by Plato dealing with the composition and structure of the ideal state.

The Republic (Greek: Πολιτεία) is an influential work of philosophy and political theory by the Greek philosopher Plato, written in approximately 390 B.C.

The original title of the work is the Greek word πολιτεία. The Republic, which is the traditional English translation of the title, is somewhat of a misnomer, taken from Cicero's Latin. The Greek title Politeia is derived from the word polis, which can roughly correspond to the modern term "city"; or, in this case, "city-state".

The Roman Republic was established in 509 B.C. after the overthrow of the last of the seven kings, Tarquinius Superbus. It was superseded by the Roman Empire in 27 B.C.