A psychoanalyst is someone who treats people by using psychoanalysis — that long, careful talking that looks for hidden causes. They are trained in that method. They are not automatically a psychiatrist. A psychiatrist is a medical doctor who treats mental illness, often with medicine. A psychoanalyst may or may not be that kind of doctor; the name marks the talking training, not the medical degree. Some people are both. You meet the word in books and in older or more specialist talk about therapy. In everyday Taiwan you are more likely to hear 心理師 or 精神科醫師; psychoanalyst names a more specific kind of therapist.