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equilibrium

ee-kwuh-LIB-ree-um /ˌiːkwɪˈlɪbriəm/

nounC1GREGMATSATCAT

academicformal

A state in a game or system where no participant has an incentive to change their strategy unilaterally.

Implies a stable balance of opposing forces or decisions rather than mere physical rest.

The story behind the word. Borrowed from Neo-Latin in the 17th century, combining 'aequus' (equal) and 'libra' (scale or balance). It originally described physical balance before economics adopted it to describe stable systems of competing choices.

Word relationships

balance: 'Balance' is a general term for equality of weight or force, whereas 'equilibrium' specifically denotes a steady state produced by counteracting dynamic forces.
stasis: 'Stasis' carries a negative connotation of inactivity or stagnation, while 'equilibrium' describes functional stability.

instability: 'Instability' implies a system prone to sudden shifts, directly opposing the self-sustaining nature of an equilibrium.
disequilibrium: 'Disequilibrium' explicitly denotes a disruption in the balance of interacting forces.

Commonly confused with

equity: 'Equity' means fairness or financial stock ownership, whereas 'equilibrium' refers to physical or strategic balance.

Word family

equilibrate (verb): To bring into or reach a state of balance.
equilibration (noun): The act or process of achieving balance.

Collocations

Nash equilibrium
reach equilibrium
market equilibrium
unstable equilibrium

Idioms & expressions

restore equilibrium
maintain equilibrium

Example sentences

"An equilibrium point is a combination of strategies such that no player has an incentive to deviate." Game Theory Foundations
"The pricing model reached a stable equilibrium after weeks of volatile fluctuations between the two rival airlines." Market Analysis

Memory hook

Think of EQUAl LIBRAs (scales) staying completely level. Equal scales in steady balance.

When not to use

Do not use to describe emotional calmness unless speaking metaphorically; use 'composure' or 'serenity' instead.

Fun facts

John Nash won the Nobel Prize in Economics largely for defining the conditions under which non-cooperative games reach an equilibrium.