Term for Japanese immigrants originating from the Japanese language term for "first generation." In the American context, the term is generally understood to apply to those who migrated prior to the cessation of Japanese immigration to the U.S. under the dictates of the Immigration Act of 1924, the bulk arriving after 1885. The vast majority of Issei were thus middle-aged or older during World War II.
Other generational terms include "Nisei" (second generation) for the American born children of the Issei, "Sansei" (third generation) for the grandchildren of the Issei and "Yonsei" (fourth generation) for their great-grandchildren. Postwar immigrants from Japan are understood to be a distinct group sometimes referred to as "Shin-Issei," the prefex "shin" being "new" in Japanese.