Why is the ninth month called September?
1844, American English, from the name of Jacob Amman, 17c. Swiss Mennonite preacher who founded the sect. Originally spelled Omish, which reflects the pronunciation in Pennsylvania German dialect. As a noun, by 1884.
A group of Protestants who broke away from the Mennonites in the seventeenth century. The Amish live in close communities, farm for a living, and do without many modern conveniences, such as telephones, automobiles, and tractor-drawn plows.
Note: Some of the Pennsylvania Dutch are Amish.