A more thorough explanation:

Definition: An alienist is a type of psychiatrist who specializes in assessing the mental health of criminal defendants. They determine whether the defendant is sane and capable of standing trial.

Example: During a high-profile murder trial, the defense team hired an alienist to evaluate the defendant's mental state and determine if they were fit to stand trial.

Explanation: In this example, the alienist is brought in to assess the defendant's mental health and determine if they are capable of standing trial. This is a common role for an alienist in the legal system.