A donut is a round, deep fried cake, usually with a hole in the center. Your favorite breakfast might be a chocolate donut and a cup of coffee.
The word donut is primarily used in the US as an alternative spelling to "doughnut." Either way you spell it, a donut is a delicious, sweet treat that's often glazed or iced, and comes in different varieties, including donuts filled with jelly or cream. Donut historians disagree about the origin of the fried delicacy, although there's consensus that "dough-nuts" were first mentioned in print in 1808, while the donut spelling became popular about 100 years later.