Wikipedia gives you a good definition and a very large list of areas. There's also the "Simple English" wikipedia. They give a very short and good definition for Physics. See...
Physics is the study of matter and its movement through either space or time. It also studies what effects different concepts have on matter - concepts such as energy, lift, gravity, or force.
I do not know what "division of physics" specifically refers to. If you are looking for the axiomatization of physics (one of Hilbert's problems), read the article below:...