1. Refers to the changes from one equilibrium state, or steady state, to another that take place within a system. For example, in a heating process, heat is transferred to the system from the surroundings.
2. A term used in process control to describe the collective functions performed in and by the process in which the process variables such as temperature, pressure, flow, and level are controlled.
3. A shorthand for chemical process, which is a collective description of the way that useful chemical products are manufactured from raw materials through chemical, physical, or biochemical means.