Origins
The word 'pilgrimage' entered Middle English around 1200 from Old French 'pelerinage,' which derives from 'pelerin' (pilgrim). The Old French form came from Late Latin 'peregrīnus,' meaning 'foreigner' or 'traveler from abroad,' which in Christian Latin specialized to mean a person undertaking a religious journey. The Latin word breaks down into 'per' (through, across) and 'ager' (field, land, territory), making a 'peregrīnus' literally 'one who goes through the fields' — that is, through foreign countryside, beyond the boundaries of home.
Latin 'ager' descends from Proto-Indo-European *h₂eǵros (field, open land), a root with wide distribution in the daughter languages. Greek 'agrós' (field) gave English 'agriculture' and 'agrarian.' The Germanic cognate, through Proto-Germanic *akraz, gave Old English 'æcer' and modern English 'acre' — originally a measure of land a yoke of oxen could plow in a day, now a standardized unit. Thus the word 'pilgrimage' contains, hidden in its etymology, the very landscape the pilgrim traverses.
In classical Latin, 'peregrīnus' had no religious connotation. It simply meant 'foreign' or 'from abroad.' Roman law distinguished between 'cīvis' (citizen), who had full legal rights, and 'peregrīnus' (foreigner), who had limited standing. The 'praetor peregrīnus' was the Roman magistrate who handled legal disputes involving non-citizens. The semantic shift from 'foreigner' to 'religious traveler' occurred in the fourth and fifth centuries as Christianity became the dominant religion of the Roman Empire. The Christian understanding of earthly life as a 'peregrinatio' — a sojourn in a foreign land, far from one's true home in heaven — invested the word with spiritual meaning. St. Augustine's theology of the 'civitas peregrina' (the pilgrim city of God wandering through the earthly world) was influential.
Development
The physical practice of pilgrimage — journeying to holy sites — developed early in Christianity. By the fourth century, the Holy Land, Rome, and various martyr shrines attracted travelers from across the Mediterranean world. The Spanish nun Egeria left a detailed account of her pilgrimage to Jerusalem and the Sinai around 381–384 CE. As the medieval period progressed, the major pilgrimage routes became deeply established: the Camino de Santiago to Compostela in northwestern Spain, the via Francigena from Canterbury to Rome, and the sea routes to Jerusalem.
Chaucer's 'Canterbury Tales' (c. 1387–1400) provides the most famous literary portrait of medieval English pilgrimage. His diverse group of pilgrims traveling from Southwark to the shrine of Thomas Becket at Canterbury demonstrates that pilgrimage was both a sacred act and a social occasion — part devotion, part holiday, part communal travel.
The Old French transformation of Latin 'peregrīnus' into 'pelerin' (and English 'pilgrim') involved significant phonological change. The sequence -er-egr- simplified, and the Latin -inus ending was replaced by the Germanic suffix -im (or possibly influenced by the proper name 'Pellegrin'). The result is that 'pilgrim' and 'peregrine' — both from the same Latin word — look quite different in English, the former arriving through popular French transmission and the latter through learned Latin borrowing.
Later History
The peregrine falcon (Falco peregrinus) shares the etymological root. Medieval falconers called it the 'peregrine' because the birds used in falconry were typically captured as they migrated through — as 'foreigners' passing over — rather than taken as nestlings from local eyries. The connection between the raptor and the religious traveler is purely etymological, but the image of a creature defined by its passage through foreign territory captures the original sense of 'peregrīnus' exactly.
In modern English, 'pilgrimage' has expanded well beyond its religious origins. People speak of pilgrimages to battlefields, ancestral homelands, literary landmarks, and places of personal significance. The word implies purposeful travel, undertaken with reverence, to a destination invested with meaning beyond the ordinary. This secular extension preserves the core sense: a journey that transforms the traveler, not merely transports them.