Which of the following best describes 'suicidal ideation'?

The concept of 'suicidal ideation' is primarily characterized by thoughts about wanting to end one's life. This definition captures the essence of what suicidal ideation entails, as it focuses on the mental process and desire related to suicide without necessarily including planning or actions.

In contrast to other aspects that might relate to suicide risk, such as specific planning steps or self-harm without the intention to die, the definition clearly emphasizes the central notion of contemplating life termination. By focusing on the desire to end one's life, this response aligns closely with established definitions used in risk assessments and clinical evaluations, thus making it the most accurate description of 'suicidal ideation'.

The other answers diverge from this central theme by either introducing elements of planning or self-harm that may not necessarily involve an intent to die, which are distinct concepts within the broader framework of suicide risk assessment.