Why is the ninth month called September?
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).
A group of English Puritans, persecuted in their own country, who emigrated to America. The first group arrived on the Mayflower in 1620. They landed at Plymouth Rock, in what is now Massachusetts, and established the Plymouth Colony, with the Mayflower Compact as their constitution. William Bradford and Miles Standish were noted leaders of the colony.