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equilibrium

/ˌiːkwɪˈlɪbriəm//ˌiːkwɪˈlɪbriəm/·noun
a state of balance between opposing forces or influences
Fig. 1 — A single weight drops onto the left pan and the beam tips, swings, and settles at a crooked angle.
01Definition

Equilibrium is balance with effort hidden inside it. From the Latin aequus (equal) and libra (scales), it names the state in which opposing forces cancel so exactly that nothing moves: supply meets demand, predator balances prey, the diver's body steadies between buoyancy and weight. Equilibrium is not the absence of forces but their perfect answer to each other — which is why disturbing one side sets the whole system searching for balance again.

02In use
  • iPrices cease to fluctuate when supply and demand reach equilibrium.
  • iiThe ecosystem maintained a delicate equilibrium between predators and prey, quick to recover from anything that might perturb it.
  • iiiAfter a volatile month, the team finally recovered its equilibrium.
03Collocations
  • reach an equilibrium
  • maintain equilibrium
  • a delicate equilibrium
  • market equilibrium
  • restore equilibrium

Family equilibrate (verb) · equilibria (plural)

04Relations

=balance, stability, steadiness, symmetry, poise

≠imbalance, instability, disequilibrium

06TOEFL & IELTS

Indispensable for TOEFL science passages — chemical equilibrium, ecological equilibrium, market equilibrium all recur. The phrase 'punctuated equilibrium' appears in evolution texts. For IELTS essays, 'strike/maintain a balance' is the everyday register and 'reach an equilibrium' the formal one. Plural, rarely needed: equilibria.

07Asked
What is equilibrium in chemistry?
The state where a reversible reaction's forward and reverse rates become equal, so the amounts of reactants and products stop changing. Crucially it is dynamic, not dead: both reactions keep running at full speed, just at matching rates. Nothing appears to happen because the two directions exactly cancel — balance held through constant motion.
What is market equilibrium in economics?
The price at which the quantity buyers want equals the quantity sellers offer — supply meets demand and the price stops moving. Above it, unsold goods push the price down; below it, shortages push it up. Like the chemical kind, it is a balance of opposing pressures, each correcting any drift away from the point.
What is the difference between static and dynamic equilibrium?
Static equilibrium is balance at rest — a book on a table, forces cancelling with nothing moving (in chemistry, a reaction that has genuinely stopped). Dynamic equilibrium is balance maintained through ongoing activity — a reaction running both ways at equal rates, or a population whose births and deaths offset. One is stillness; the other is motion that nets to zero.
What does 'loss of equilibrium' mean?
Two things at once. Physically, it is losing your sense of balance — dizziness, unsteadiness, the body unable to stay upright. Figuratively, it is losing composure: 'she regained her equilibrium' means she recovered her calm. Both keep the word's core — a steady balance disturbed, then searched for again.
What is the plural of equilibrium?
Equilibria, keeping the Latin ending — 'the system has two stable equilibria'. The anglicised 'equilibriums' is accepted informally but reads as less careful in scientific writing. You will rarely need the plural outside physics, chemistry, and economics, where multiple balance points genuinely coexist.
What is the difference between equilibrium and balance?
Mostly register. Balance is the everyday word ('work-life balance', 'keep your balance'); equilibrium is its formal, scientific twin, pronounced ee-kwi-LIB-ree-um. In an essay, 'strike a balance' is natural speech and 'reach an equilibrium' is technical precision. The scene above is equilibrium — a beam that stays dead level as two equal weights land at once.