# equilibrium

Pronunciation: US say "ee-kwuh-LIB-ree-um" /ˌikwəˈlɪbɹiəm/; UK say "ek-wi-LIB-ree-uhm" /ɛkwɪˈlɪbɹɪəm/

## Noun

1. The state of a system in which opposing influences balance one another, so that there is no overall change.
   - Simple: A state where different forces or pressures balance each other, so nothing changes overall.
   - _Wolves and deer in the valley eventually reached a natural equilibrium that held for decades._
   - _Any new tax upsets the market's equilibrium, at least for a while._
2. Mental balance; a steady, composed state of mind.
   - Simple: A calm, steady state of mind.
   - _It took her a week of quiet to recover her equilibrium after the funeral._
   - _One rude email can wreck my equilibrium for the whole morning._
3. In physics, the state of a body at rest or moving uniformly, in which all the forces acting on it add up to zero.
   - Simple: The state of an object when all the forces on it cancel out, so it stays still or moves steadily.
   - _A bridge is designed so that every joint stays in equilibrium under its expected load._
   - _A car cruising at constant speed on a level road is in equilibrium, since the engine's push exactly matches drag and friction._
4. In chemistry, the state of a reversible reaction in which the forward and reverse reactions proceed at the same rate.
   - Simple: In chemistry, the point when a reaction runs both ways at the same speed, so the amounts stop changing.
   - _At equilibrium, ammonia is formed and broken down at exactly the same rate._
   - _Chemists raise the pressure to shift the equilibrium toward the product they want._

## Origin

From Latin aequilībrium, formed from the word for "equal" and lībra ("balance").

Source: DictionaryAI, https://dictionaryai.com/define/equilibrium (written from Wiktionary data, CC BY-SA 4.0: https://creativecommons.org/licenses/by-sa/4.0/).