[mech.a.nism] n (1662) 1 a: a piece of machinery b: a process or technique for achieving a result
2: mechanical operation or action: working 2
3: a doctrine that holds natural processes (as of life) to be mechanically determined and capable of complete explanation by the laws of physics and chemistry
4: the fundamental physical or chemical processes involved in or responsible for an action, reaction, or other natural phenomenon (as organic evolution)