Definition from Wiktionary, the free dictionary
mechanism (plural mechanisms)
- Within a machine or machinery; any mechanical means for the conversion or control of motion, or the transmission or control of power.
- Any combination of cams, gears, links, belts, chains and logical mechanical elements.
- A group of objects or parts that interact together. (as in Political machine)
- A mental, physical, or chemical process.
- (philosophy) A theory that all natural phenomena can be explained by physical causes.
Derived terms 
mechanical means for the conversion or control of motion