1.the atomic process that occurs during a chemical reaction;
he determined unique mechanisms for the photochemical reactions
2.the technical aspects of doing something;
a mechanism of social control
3.a natural object resembling a machine in structure or function;
the mechanism of the ear
4.(philosophy) the philosophical theory that all phenomena can be explained in terms of physical or biological causes
5.device consisting of a piece of machinery; has moving parts that perform some function