I used to think that people who think highly of their abilities are labeled presumptuous but when I looked it up in the dictionary, I was wrong. So, what is the proper term (formal and informal) for those who: a) think that they are intelligent when they're just average in class? b) think that they have a beautiful voice when it's not? c) think that they are good at doing something (arts, drawing, painting) when they're not? Thanks.