The earliest known reference to French toast is in the Apicius, a collection of Latin recipes dating to the 4th or 5th century, where it is described as simply aliter dulcia ("another sweet dish"). The recipe says to "slice fine white bread, remove the crust, and break it into large pieces. Soak these pieces in milk and beaten egg, fry in oil, and cover with honey before serving."
A fourteenth-century German recipe uses the name Arme Ritter ("poor knights"), a name also used in English and the Nordic languages. Also in the fourteenth century, Taillevent presented a recipe for "tostées dorées". Italian 15th-century culinary expert Martino da Como offers a recipe. 
The usual French name is pain perdu (French: [pɛ̃ pɛʁdy] (listen), "lost bread", reflecting its use of stale or otherwise "lost" bread — which gave birth to the metaphoric term pain perdu for sunk costs. It may also be called pain doré, "golden bread", in Canada. There are fifteenth-century English recipes for pain perdu.
An Austrian and Bavarian term is pafese or pofese, from zuppa pavese, referring to Pavia, Italy. The word "soup" in the dish's name refers to bread soaked in a liquid, a sop. In Hungary, it is commonly called bundáskenyér (lit. "furry bread").