Equilibrium refers to a Piagetian term for the state of Balance between Assimilation and accommodation, thereby allowing knowledge to be incorporated.
In Piaget's theory,Equilibrium is th
e balance that every organism strives to attain in which organized structures (sensory, motor, or cognitive) provide effective ways of interacting with the environment.
Other /More definition:
Equilibrium refers to a state of zero acceleration in which there is no change in the speed or direction of the body.
Lexicon of Psychology - Terms, Treatments, Biographies,