The common shortened American-English spelling of “doughnut” is “donut.” Both spellings are used in the United States, but “donut” is the simplified form readers often see in brand names and everyday writing.
“Doughnut” is the older traditional spelling. Early American uses included “dough-nuts,” a name referring to small, rounded cakes made from fried dough. The shorter “donut” spelling appeared in print by 1900 and became increasingly popular during the 20th century.
A frequently cited influence was the Display Doughnut Machine Corporation, a New York company that promoted the shorter spelling in the 1920s. The company hoped its automated equipment would appeal to international buyers who might find “doughnut” harder to pronounce.
The two forms are not different foods: a glazed ring, a filled pastry, or a cake-style version can be called either a doughnut or a donut. “Doughnut” remains widespread, while “donut” is especially familiar through names such as Dunkin’ Donuts, founded in 1950.