side effect; adverse reaction
operation (working) of the mind
autopurificatory activity (in the natural world)
point of action (e.g. of a lever)
bactericidal action; germicidal action
stimulant effect (e.g. caffeine)
(mutual) interaction; reciprocal action; interplay
adverse effect; untoward effect; adverse drug reaction; ADR
mechanism of action (e.g. drug); mode of action; action mechanism
action-reaction law; Newton's third law of motion
efficient cause (one of Aristotle's four fundamental types of answer to the question "why?")
(the act of) disintegration
catalytic action; catalysis
assimilation; metabolism; anabolism
state action; national action
carbon assimilation; carbon fixation
principle of least action
sifting out; weeding out; selection; sorting
crystallization differentiation
carbon assimilation; carbon fixation