What is the meaning of "res judicata" in legal terms?

Res judicata is a fundamental legal doctrine that prevents the re-litigation of cases that have already been judged on their merits. The principle asserts that once a court has issued a final judgment in a case, that judgment is conclusive and cannot be contested in any future legal action between the same parties regarding the same issue or cause of action. This doctrine promotes judicial efficiency and finality, ensuring that parties cannot keep bringing the same dispute to court repeatedly, which would burden the legal system and create uncertainty for the parties involved.

The other options do not align with the definition and purpose of res judicata. The principle concerning appeals on verdicts relates to the right to challenge a court's decision, which is not covered by res judicata. Similarly, while resolving disputes in court is a general purpose of the judicial system, it does not specifically describe the effect of a prior judgment as res judicata does. Lastly, the concept of evidence admissibility in court pertains to rules of evidence rather than the broader principle of previously adjudicated matters. Hence, the correct understanding of res judicata is encapsulated in the notion of preventing the retrial of cases already adjudicated.