equilibrium
/ˌiːkwɪˈlɪbrɪəm/ /ˌɛkwɪˈlɪbrɪəm/
noun equilibria
mass noun
1 A state in which opposing forces or influences are balanced.
1.1 A state of physical balance.
1.2 A calm state of mind.
Origin
Early 17th century (in the sense ‘well-balanced state of mind’): from Latin aequilibrium, from aequi- ‘equal’+ libra ‘balance’.
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Bob's outwardly calm demeanor belied his inner turmoil. He kept things in equilibrium by burning rapidly through his emotional resources.