Rostagnus is a Latinization of a Germanic given name common in the Middle Ages, especially in Occitania.
It derives from Proto-Germanic *Hrōþi- "fame" and *stainaz "stone".
It is attested in the Old High German form Hruodstein.
[1][2] Numerous other Latin spellings are known: Rostandus,[3] Rustandus,[1] Rostaignus, Rostangnus, Rostannus,[4] Rystagnus and Restagnus.
[5] In vernacular documents in England and Romance-speaking areas, the name appears as Rostaing,[3] Rostand, Rostan,[4] Rustand, Rustant, Rustan, Rodstein, Rostein,[1] Rostain,[2] Rostang and Rostagne.