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e·qui·lib·ri·um (ēkwə-lĭbrē-əm, ĕkwə-)
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n. pl. e·qui·lib·ri·ums or e·qui·lib·ri·a (-rē-ə)
1. A condition in which all acting influences are canceled by others, resulting in a stable, balanced, or unchanging system.
2. Mental or emotional balance.
3. Physics The state of a body or physical system at rest or in unaccelerated motion in which the resultant of all forces acting on it is zero and the sum of all torques about any axis is zero.
4. Chemistry
a. The state of a chemical reaction in which its forward and reverse reactions occur at equal rates so that the concentration of the reactants and products does not change with time.
b. The state of a system in which more than one phase exists and exchange between phases occurs at equal rates so that there is no net change in the composition of the system.

[Latin aequilībrium : aequi-, equi- + lībra, balance.]

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
 

Indo-European & Semitic Roots Appendices

    Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

    Indo-European Roots

    Semitic Roots

    The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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