Faith is a versatile word. I would disagree that it is a belief in something that cannot be proven, because people take things in science ‘on faith’ even though it has yet to be proven, or is in the process of being proven.
Take Evolution as an example. By definition, it is still a theory, but a lot of people speak of it as fact, and many would even call it fact, and yet, it is still considered a theory. So, even though it is still a theory, many people take it ‘on faith’ that Evolution is true. Now, does this mean that it cannot be proven, no, as it is in a process. This is why I would relate faith with trust. People trust that science is good enough to ‘prove’ Evolution is true, even if it has not been proven yet. Even faith requires evidence or ‘givens’ to base an idea on.
(Do not turn this into a debate about Evolution)
So, I might define faith as “trusting that something is true”. I can take this further. We have enough scientific evidence to suggest that the sun will rise tomorrow. And in turn, I can have faith that the sun will in fact rise tomorrow. Since it isn’t tomorrow yet, I do not know if the sun will rise, but I have enough evidence to suggest that it will. And if tomorrow comes and the sun rises, then my faith has proven fruitful.
So, again, faith doesn’t mean that something can’t be proven, but is (in general) trusting that something is true.