Mechanism (?), n. [Cf. F. mécanisme, L. mechanisma. See Mechanic.] 1. The arrangement or relation of the parts of a machine; the parts of a machine, taken collectively; the arrangement or relation of the parts of anything as adapted to produce an effect; as, the mechanism of a watch; the mechanism of a sewing machine; the mechanism of a seed pod.[1913 Webster]
2. The series of causal relations that operate to produce an effect in any system; as, the mechanism of a chemical reaction.[PJC]
3. Mechanical operation or action.[1913 Webster]
He acknowledges nothing besides matter and motion; so that all must be performed either by mechanism or accident.
4. (Kinematics) An ideal machine; a combination of movable bodies constituting a machine, but considered only with regard to relative movements.[1913 Webster]