/ˌɛkwəˈnɪmɪti/
[noun] A calm, steady state of mind, especially in difficult or stressful situations. If someone handles bad news with equanimity, they stay composed and don't panic or become upset.
Equanimity literally means 'equal mind' — the Romans believed a balanced soul was the highest form of human strength.
Equanimity traces its roots to two Latin words joined together: aequus, meaning 'equal' or 'level', and animus, meaning 'mind' or 'spirit'. When the Romans pressed these two ideas together into the word aequanimitas, they created something beautiful — the idea of a mind so well-balanced that no storm of emotion could tip it to one side. This was not passive numbness, but an active, almost heroic inner steadiness.
The concept was central to Stoic philosophy, and Roman writers used aequanimitas with great seriousness. The philosopher-emperor Marcus Aurelius wrote extensively about this quality in his private journal, which we now call the Meditations. For the Stoics, aequanimitas was one of the highest virtues — the ability to receive both fortune and misfortune without losing one's inner balance. Cicero also used the term, describing it as the mark of a wise and virtuous person.
The word traveled from classical Latin into the vocabulary of educated Europeans through the Renaissance revival of ancient texts. Scholars writing in Latin kept the original form aequanimitas alive, and from there the anglicised version equanimity entered the English language in the early 17th century. The Oxford English Dictionary records uses from around the 1610s, a period when English writers were drawing heavily on Latin and Greek ideas to build their own philosophical vocabulary.
In its early English use, equanimity was closely tied to moral and philosophical writing. It described the composed acceptance of God's will in religious texts, and the wise indifference to worldly suffering in philosophical essays. Over the following two centuries, the word gradually moved from purely philosophical contexts into more everyday writing, where it came to describe any calm and steady response to difficulty — not just the heroic composure of a philosopher, but the quiet steadiness of a good doctor, a patient teacher, or anyone facing hardship with grace.
The two Latin roots have given English a surprising number of other words. Aequus, meaning 'equal' or 'level', passed through Old French as equal and gave us equal, equality, and equator — the imaginary line that divides the Earth into two perfectly level halves. It also gave us equable, meaning pleasantly steady in mood or climate. Animus, meaning 'mind' or 'spirit', gave us animal, animate, and unanimous — that last word combining Latin unus ('one') with animus to mean 'of one mind'. Equanimity, then, is a word that quietly carries within it the whole philosophical ideal of a mind as flat and untroubled as a still horizon.