Origins
The English word 'virtue' entered the language in the early thirteenth century from Old French 'vertu,' from Latin 'virtūs.' The Latin word's etymology is transparent: 'virtūs' derives from 'vir' (man, male person, hero), with the abstract noun suffix '-tūs,' making its literal meaning 'manliness' or 'the quality of being a man.' The PIE root is *wiHrós (man), which also produced Sanskrit 'vīra' (hero, man), Lithuanian 'vyras' (man), Old Irish 'fer' (man), and Old English 'wer' (man — surviving only in 'werewolf,' literally 'man-wolf').
In early Roman culture, 'virtūs' denoted the specific qualities expected of an ideal Roman male: physical courage, military valor, strength of character, and the willingness to sacrifice for the republic. The elder Cato embodied this archaic 'virtūs' — austere, warlike, uncompromising. The word was inseparable from the battlefield and the forum; it belonged to the world of men at arms and men in debate.
The decisive transformation came with Cicero, who in the first century BCE deliberately expanded 'virtūs' to encompass the four cardinal virtues of Greek philosophy: prudentia (prudence), iustitia (justice), fortitūdō (fortitude), and temperantia (temperance). This expansion detached 'virtūs' from its exclusively masculine and martial origins and aligned it with the broader Greek concept of 'aretē' (excellence, virtue), which could apply to any domain of human achievement. Cicero's redefinition was enormously influential: through his philosophical works, 'virtūs' became the standard Latin term for moral excellence in general.
Development
Christian theology further transformed the word. The Church Fathers added the three theological virtues — faith, hope, and charity — to Cicero's four cardinal virtues, creating the seven virtues that medieval moral theology set against the seven deadly sins. In this framework, 'virtūs' lost its last traces of gender specificity: the Virgin Mary was held up as the supreme exemplar of virtue, and the word's original meaning of 'manliness' was completely eclipsed by the universal meaning of 'moral goodness.'
In Middle English, 'vertu' carried an additional sense now largely lost: power, efficacy, or potency. Chaucer's Canterbury Tales opens with April's 'shoures soote' (sweet showers) that have pierced the drought 'with vertu of which' the flowers spring — here 'vertu' means 'power' or 'efficacious force,' not moral excellence. This sense survives in modern English in the phrases 'by virtue of' (by the power of) and 'healing virtue' (curative power). It derives from the Latin usage in which 'virtūs' could mean the inherent power or capacity of a thing — the 'virtue' of a medicinal herb was its potency.
The Italian word 'virtù' took a dramatically different path under the influence of Machiavelli, who in 'The Prince' (1513) used it to mean something closer to the original Roman sense: political cunning, decisive action, and the ability to impose one's will on fortune — qualities that might or might not align with conventional morality. Machiavelli's 'virtù' has never been successfully translated into a single English word; it hovers between 'virtue,' 'prowess,' 'skill,' and 'ruthlessness,' reminding us that the Latin original was always more complex than simple moral goodness.
Latin Roots
The word 'virtual,' now ubiquitous in computing, descends from the same root through medieval Latin 'virtuālis' (having the power or virtue of). A 'virtual' thing has the virtue — the power, the essence — of the real thing without being the real thing in physical form. 'Virtual reality' is thus, etymologically, 'reality-by-virtue-of' — a reality that possesses the essential power of the real without the material substance. This usage, which might seem thoroughly modern, in fact preserves the medieval 'potency' sense of virtue more faithfully than the moral sense does.
The word 'virtuoso' — originally an Italian term for a person of exceptional skill or learning — also belongs to this family. In the seventeenth century, a 'virtuoso' was a connoisseur, a person of wide learning and refined taste. By the nineteenth century, it had narrowed to mean a supremely skilled musician or artist. The journey from 'manliness' to 'musical mastery' — passing through valor, moral excellence, inherent power, and connoisseurship — is one of the most extravagant semantic odysseys in the history of the English language.