Over recent years the word "narcissist" has become the cheapest diagnosis in circulation. It gets handed to the ex, the boss, the neighbour, the politician, the relative who did not call on your birthday. The problem is that when a word means everything, it stops meaning anything.

Psychologist Sara Navarrete starts from the opposite end: "Having narcissistic traits is not the same as having narcissistic personality disorder. In fact, every one of us has a certain degree of narcissism." And she adds that in a healthy dose, it is part of healthy self-esteem.

Healthy narcissism, she says, looks entirely ordinary: feeling that you have worth, enjoying recognition, caring how you look. None of that is a defect. The pathological version is something else - it is rigidity and a need to dominate relationships, not merely satisfaction with your own image.

Navarrete distinguishes two profiles, and the second is the one nobody recognises. The first is the grandiose: arrogant, dominant, exactly what people picture when they say the word. The second is the vulnerable one - extremely sensitive to criticism, easily wounded, seemingly anything but a narcissist. Which is why it goes unnoticed.

The strongest sentence in the whole interview is the one that demolishes the popular picture entirely: narcissism does not always mean excessive self-love. "Often it means a constant need for others to maintain a sense of worth that the person cannot sustain from within." In other words, what looks from the outside like an oversized ego is, from the inside, a hole somebody else has to keep filling.

The signs that genuinely mean something, according to her: an intense need for admiration, difficulty admitting a mistake, low tolerance of criticism, and an inability to truly grasp another person's perspective. But one bad day is not a diagnosis. What you are looking for is a pattern - the same behaviour, in different situations, with different people, over a long stretch of time.

Here, this word is most often thrown into an argument, as the last card when the others have run out. Which is why the distinction is worth keeping: a person who likes being praised is not ill. A person who cannot function without it - is something else. And only one of the two is a diagnosis, one that is not made over the phone, or in a comment thread.