Nougat is a French word that is not quite French. It comes from Occitan, the old language of southern France.
In Old Occitan, noga or nuga meant "nut," and nogat was a nut cake: literally something "nutty." Behind it is Latin nux, "nut." Etymologists reconstruct a Vulgar Latin form, nucatum, as the bridge between the two. Standard French absorbed the southern word in the 1700s, and English borrowed nougat from French in 1827.
The earliest record of the Occitan word is a little older. A dietetics book, the Thresor de santé of 1607, uses nogat for a confection from Provence and Languedoc. The town most linked to it is Montélimar. In 1701 its residents presented two royal dukes with about 43 kilograms of nougat. The town's mayor, Émile Loubet, later President of France, promoted it heavily in the 19th century.
Montélimar has a legend that the agronomist Olivier de Serres planted the almond trees that made nougat possible. The record does not support it. Almonds were grown in Provence by the 14th or 15th century, long before his time, and were sold at the Lyon fairs from 1474.
The confection is far older than its name. The earliest well-attested recipes for something like nougat come from a 10th-century Baghdad cookbook, where it was called nāṭif. Southern Europe had its own versions by the 1400s, and they kept their own names. Spanish turrón and Italian torrone come from Latin torrere, "to roast."
So a sweet that is mostly sugar, honey and egg white carries a name that only mentions the nuts. The Latin nux also survives in a more scientific word. Nucleus first meant "kernel of a nut," from a Latin diminutive meaning "little nut." Old English hnutu, the ancestor of nut, comes from the same ancient root.