equilibrium

UK: /ˌiːkwiˈlɪbriəm/

US: /ˌikwəˈlɪbriəm, ˌɛkwə-/

US: (ē′kwə lib′rē əm, ek′wə-)

Inflections of 'equilibrium' (n):

equilibriums

npl

equilibria

npl

WordReference Random House Learner's Dictionary of American English © 2025

e•qui•lib•ri•um /ˌikwəˈlɪbriəm, ˌɛkwə-/   n. [uncountable]

1. a state of rest or balance between opposing forces, powers, or influences.
2. mental or emotional balance;
   equanimity.

See -equa-, -libra-.

WordReference Random House Unabridged Dictionary of American English © 2025

e•qui•lib•ri•um  (ē′kwə lib′rē əm, ek′wə-), n., pl. -ri•ums, -ri•a 

(-rē ə). 
1. a state of rest or balance due to the equal action of opposing forces.
2. equal balance between any powers, influences, etc.; equality of effect.
3. mental or emotional balance;
   equanimity:
   The pressures of the situation caused her to lose her equilibrium.
4. Chemistry the condition existing when a chemical reaction and its reverse reaction proceed at equal rates.

• Latin aequilībrium, equivalent. to aequi- equi- + lībr(a) balance + -ium -ium
• 1600–10

e•quil•i•bra•to•ry  (i kwil′ə brə tôr′ē, -tōr′ē, ē′kwə lib′rə-, ek′wə-), adj.  Synonyms

• 1. equipoise, steadiness, stability.

Collins Concise English Dictionary © HarperCollins Publishers::

equilibrium / ˌiːkwɪˈlɪbrɪəm/ noun ( -riums, -ria / -rɪə/)

1. a stable condition in which forces cancel one another
2. a state or feeling of mental balance; composure
3. any unchanging condition or state of a body, system, etc, resulting from the balance or cancelling out of the influences or processes to which it is subjected
   See thermodynamic equilibrium
4. a state of rest or uniform motion in which there is no resultant force on a body
5. a state of bodily balance, maintained primarily by special receptors in the inner ear

Etymology: 17th Century: from Latin aequilībrium, from aequi- equi- + lībra pound, balance