Find out about catalytic reaction & catalyst. Check out its characteristics, types, examples, kinetics, & mechanism . Learn catalyzed vs. uncatalyzed reactions. The meaning of MECHANISM is a piece of machinery. How to use mechanism in a sentence. The mechanism of enzyme action is related with the enzyme ’s specificity and the transition state of the reactants or substrates. Mechanism : the fundamental physical or chemical processes involved in or responsible for an action, reaction or other natural phenomenon. Machine: an assemblage of parts that transmit forces, motion and energy in a predetermined manner. Simple Machine: any of various elementary mechanisms having the ...