"febrile epidemic disease of the tropics," 1828, from West Indian Spanish dengue, from an African source, perhaps Swahili dinga "seizure, cramp," with form influenced by Spanish dengue "prudery" (perhaps because sufferers walk stiffly and erect due to the painful joints which characterize the disease). The disease is from East Africa and was introduced into the West Indies in 1827.
1926 in the U.S. geographical sense, from earlier Midwestern (1889) in reference to a group of states originally listed as West Virginia, Kentucky, Tennessee, Missouri, Kansas, and Arkansas; it now generally refers to states somewhat north and west of these (according to the U.S. Census Bureau, Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin). Related: Midwesterner.
"American born of Japanese parents," from Japanese ni- "second" + sei "generation." Use of the word was limited to U.S. West Coast until c. 1942.