Today my teacher told me that there is no definition for energy , because according to him it cannot be described. He then went on justfying it by comparing it to Good and Evil , and Big and small. I said that it can and should have a definition because unlike big and small , or good and evil , it exists and is not a comparison of things , so thus can have a definition. I gave him my definition of energy which is "A force that has the ability to move matter from one point in space to another" , he said that I was wrong because it cannot be described and that every other physicists would agree with him.I also went and look in the physics text book and looked up the definition of energy and I got "A non - matter property that is capable of changing matter." Is he right? Can energy be defined? If it can be defined what is your definition of it?