Hi,
Indeed the definition you give here of "bitcoin" is right. However I feel it lacks a bit of what bitcoin truly is. It is a crypto-currency (which means you have no printed bills nor emitted tangible coins), it gathers a whole community trying to make the most and understand this new technology and.. Well it is a world full of fraud, scams, with its own rules and quite hard to grasp for beginners... but it is also a place of opportunities, new business models and alternative ways of thinking.
You see? I understand that regarding school work, this definition can be rather overloaded with feelngs but.. Well, this is my true definition!