late O.E., from L. September,
"seven" (see seven
). So called because it was the seventh month of the old Roman calendar, which began the year in March; Julian calendar reform (46 B.C.E.) shifted the new year back two months. For -ber
suffix, see December
. Replaced O.E. hærfestmonað, haligmonað. Septembrist
(1840) in Fr. history refers to the massacre of the political prisoners in Paris, Sept. 2-5, 1792.