A more thorough explanation:

Definition: To take legal action against someone by filing a lawsuit.

Example 1: John decided to sue his former employer for wrongful termination.

Example 2: The company threatened to sue the individual for breach of contract.

Explanation: When someone sues another person or entity, they are taking legal action against them by filing a lawsuit. This means that they are asking a court to intervene and make a decision about a dispute or issue between them and the other party. In example 1, John is taking legal action against his former employer for firing him unfairly. In example 2, the company is threatening to take legal action against an individual for breaking a contract they had agreed to.