The quality of being equable; evenness of temper, consistency, or uniformity in manner or condition.
From equable + -ity (quality or state of). Equable comes from Latin aequabilis (equal, uniform), from aequus (equal). The suffix -ity converts the adjective into a noun expressing the abstract quality.
This word was huge in Victorian psychology and temperament theory—people literally classified others as having 'equability' or lack thereof, believing it was a measurable personality trait that determined your success in life and society.
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