I think the word "genius" best describes a body of work, or an accomplishment that changes the world in a surprising way, that is, genius is not just intelligence, it is being in the right place at the right time, with the right people around you (Einstein's wife was reportedly brilliant as well), and then being driven to understand and describe the world back to people through new science or art. It means that a person has enough resources and few distractions that occupy their minds.
In other words, 'genius' to me describes a situation, not just the person.