noun

1. Obsolete natural philosophy
2. 1. the science dealing with the properties, changes, interactions, etc. of matter and energy in which energy is considered to be continuous (classical physics), including electricity, heat, optics, mechanics, etc., and now also dealing with the atomic scale of nature in which energy is considered to be discrete (quantum physics), including such branches as atomic, nuclear, and solid-state physics
   2. a specific system of physics
3. a book or treatise on any of these

Etymology: transl. of L physica, physics < Gr (ta) physika (lit., natural things), name given to the physical treatises of Aristotle: see physic

plural noun