doughnut

Doughnut comes straight from dough (from Old English dāg, ultimately Proto-Indo-European *dʰeyǵʰ-) plus nut (from Old English hnutu). It's first attested in 1809, in Washington Irving's Knickerbocker's History of New York.

The name likely started because the earliest versions were small, nut-sized balls of fried dough, or because 'nut' was once used more loosely for any small rounded cake or cookie. The now-familiar ring shape only became common in the twentieth century, long after the name was already fixed.

It shares its first half with dough itself, and its second half with nut — the word is literally a compound of the two, no hidden relatives beyond that.