Homeostasis [hoh-mee-uh-stey-sis]

noun

1.the tendency of a system, especially the physiological system of higher animals, to maintain internal stability, owing to the coordinated response of its parts to any situation or stimulus that would tend to disturb its normal condition or function.

2.Psychology. a state of psychological equilibrium obtained when tension or a drive has been reduced or eliminated.

-rip (via dictionary.com)