Any number of people have inquired about the origin of the name of this pastry. The dough part is easy enough, but why nut?
The term doughnut is first attested to 1809 in Washington Irving’s Knickerbocker’s History of New York. But Irving does not refer to the toroidal confection that we know today. Instead, what he describes are small balls of fried dough, what we would today call doughnut holes:
An enormous dish of balls of sweetened dough, fried in hog’s fat, and called doughnuts, or olykoeks.
The nut comes from the size and shape of these balls, literally nut-like objects made out of dough.
Thoreau references oblong-shaped doughnuts, what we might today call a cruller, in an 1847 Atlantic Monthly article:
The window was...the size of an oblong doughnut, and about as opaque.
Apparently, the familiar toroidal shape did not become standard until the 20th century.
Some wags have claimed original spelling was "doughnought," referring to the hole in the middle. This is simply not true.
(Source: Oxford English Dictionary, 2nd Edition)
Copyright 1997-2017, by David Wilton