Origins
The English word 'legacy' entered the language in the fifteenth century, drawn from Medieval Latin 'lēgātia' and Old French 'legacie.' Its ultimate source is Latin 'lēgātum,' the neuter past participle of 'lēgāre,' a verb with two related but distinct meanings: to bequeath (to leave something by will) and to send as a deputy (to commission someone with legal authority). Both senses flow from 'lēx' (law), which traces to the Proto-Indo-European root *leǵ- (to collect, gather).
The connection between law and gathering is fundamental. A 'lēx' was a set of rules collected and agreed upon; 'lēgāre' was to act with the authority of that collected law. To bequeath was to transfer property through a lawful instrument — a will — and the person who received such a bequest was a 'lēgātārius' (legatee). The legal sense of 'legacy' as a specific bequest in a will remained dominant in English through the eighteenth century.
The broader meaning of 'legacy' — anything inherited from the past, whether tangible or intangible — developed gradually. By the seventeenth century, writers used 'legacy' metaphorically: a leader's legacy, the legacy of a war, the legacy of a tradition. This extension preserved the core idea of transmission across time while shedding the strictly legal framework. Today, this abstract sense is far more common than the testamentary one.
Development
The word family rooted in 'lēgāre' and 'lēx' is extensive. 'Legate' (a papal or diplomatic envoy — one sent with legal authority), 'delegate' (one sent away on a commission), 'relegate' (to send back, to demote), 'legal' (pertaining to law), 'legislate' (to make law, from 'lēx' + the root of 'agere,' to drive), 'legitimate' (in accordance with law), and 'privilege' (a private law, from 'prīvus' + 'lēx') all belong to this family. Even 'college' descends from 'collēgium' (a body of people chosen together under common rules).
In the twentieth and twenty-first centuries, 'legacy' acquired a specific technical meaning in computing and technology. A 'legacy system' is an old computer system, programming language, or application that remains in use despite being outdated. The term captures the ambivalence of inheritance: a legacy system may be valuable (it works, it holds critical data) but also burdensome (it is expensive to maintain, difficult to integrate with modern tools). When programmers speak of 'legacy code,' they echo the original Latin sense with remarkable precision — it is something bequeathed by predecessors that current users must manage.
The adjective 'legacy' applied to admissions — as in 'legacy student' at American universities, meaning a child of alumni given preferential admission — emerged in the mid-twentieth century. This usage highlights another dimension of inheritance: the advantages and obligations that flow from family connections, a social parallel to the legal bequest.
Latin Roots
Cognates in Romance languages reflect the Latin origin: French 'legs' (a bequest, with a silent 'g' and 's'), Spanish and Portuguese 'legado' (bequest; also emissary), Italian 'legato' (bequest; also a musical term meaning 'bound together'). The diversity of meanings across these cognates — from bequests to envoys to musical phrasing — illustrates how the twin senses of 'lēgāre' (to send and to leave behind) branched in different directions across different cultural contexts.