pilgrim: [12] Etymologically, a pilgrim is someone who goes on a journey. The word comes via Provençal pelegrin from Latin peregrīnus ‘foreign’. This was a derivative of pereger ‘on a journey, abroad’, a compound formed from per ‘through’ and ager ‘country’ (source of English agriculture). When it arrived in English it was still being used for ‘traveller’ (a sense which survives in the related peregrinations [16]), but the specific ‘one who journeys for religious purposes’ was well established by the 13th century.
The peregrine falcon [14] got its name because falconers took its young for hunting while they were ‘journeying’ from their breeding places, rather than from their nests. => peregrine
pilgrim (n.)
c. 1200, pilegrim, from Old French pelerin, peregrin "pilgrim, crusader; foreigner, stranger" (11c., Modern French pèlerin), from Late Latin pelegrinus, dissimilated from Latin peregrinus "foreigner" (source of Italian pellegrino, Spanish peregrino), from peregre (adv.) "from abroad," from per- "beyond" + agri, locative case of ager "country" (see acre).
Change of first -r- to -l- in most Romance languages by dissimilation; the -m appears to be a Germanic modification. Pilgrim Fathers "English Puritans who founded Plymouth colony" is first found 1799 (they called themselves Pilgrims from c. 1630, in reference to Hebrew xi:13).