The Chinese word Qi (pronounced chee) is usually translated as 'vital energy'. This is a most appropriate translation when it comes to oriental medicine: we tend to see it as 'energy' that animates our body as opposed to 'matter' which forms our body tissues. And of course it is hard for us to conceive that energy and matter could be from the same origin.
Science
However, our modern Quantum Physics now came to the conlusion that certain events in the world of quantum particles cannot be explained when we see particles simply as material objects. For example, during some experiments electrons start to behave like waves - they become prone to interference and difraction. One electron can simultaneously go through two distinct holes and interfere with itself! Modern physics explains this as a "wave-particle duality". It says the matter may be seen as wave, which is a form of energy. Click to learn how Chinese medicine treats Obstructive Emphysema.
To formalise this, Einstein came up with his famous formula: E=mc2. The meaning of it is that the potential energy of 1 m2 of matter is 90'000'000'000J, which is an enormous amount of power if it is ever released. So, it looks like energy and matter are actually one. Matter - is a trap for the energy!