equilibrium (English)
Where does "equilibrium" come from?
The word equilibrium traces its roots back to the Latin term aequilībrium, which combines 'aequus,' meaning equal, and 'lībra,' meaning a balance or pair of scales. Entering English in the 17th century, it initially described the physical state of being balanced and stable. Over time, its meaning expanded to encompass both scientific systems and states of mental composure.
Full etymology tree
- equilibrium (English), 'The condition of a system in which competing influences are balanced, resulting in no net change.'
- borrowed aequilibrium (Latin), 'A level or horizontal position, equilibrium.'
- compound aequus (Latin), 'equal'
- inherited *h₂eykʷ- (Proto-Indo-European)
- compound lībra (Latin), 'libra, Roman pound, a Roman unit of mass, equivalent to about 327 g'
- suffix -ium (Latin), 'Suffix used to form abstract nouns, sometimes denoting offices and groups. May no longer be productive.'
- compound aequus (Latin), 'equal'
- borrowed aequilibrium (Latin), 'A level or horizontal position, equilibrium.'
Updated June 2026
Etymology data from Wiktionary, CC BY-SA 4.0 · About Miraris