see doughnut. It turns up as an alternate spelling in U.S. as early as 1870 ("Josh Billings"), common from c.1920 in names of bakeries. Halliwell ("Dictionary of Archaic and Provincial Words," 1847) has donnut "a pancake made of dough instead of batter," which Bartlett (1848) writes "is no doubt the same word" as the American one.