[smt88]

Is that the psychiatric definition of disorder?

My understanding is that it has to be disagreeable to the person who has it or put others at risk (in extreme instances).

So for example, someone with synesthesia might be considered disordered only if it prevents them from being happy or taking care of themselves, while many people with synesthesia seem to enjoy it.

[lujim]

A clinically important syndrome; that is, it's a collection of symptoms (these can be behavioral or psychological) that causes the person disability or distress in social, personal, or occupational functioning.