Many resources on depression and suicide use the term "suicidal ideation" as an important sign/symptom. Some sources (e.g. Krahn, Miller, and Bergstrom, Rapid Resolution of Intense Suicidal Ideation after Treatment of Severe Obstructive Sleep Apnea, 2007) say that it alone (without anything else, like an actual suicide attempt) constitutes a medical emergency.
What is the definition of the medical term of art "suicidal ideation"? For example, does any fleeting thought or consideration of suicide as a possible option count, or is more required? Does it require a firm conclusion that suicide is the only reasonable option? Part of me suspects that the definition is "to think about suicide to the extent that such thinking rises to the level of a medical emergency", but that seems like a circular definition!
This is a definitions question. I do not need help with depression or suicide!