What’s the deal with spelling “role” with the circumflex over the “o”?
It’s the original French spelling?
The circumflex stands for an s in earlier spelling; the word was once rosle.
But I don’t know what the Latin ancestor of rosle was. Rosulus, perhaps? The OED does say that the word derives from the “roll” that contained the actor’s lines, but doesn’t give the etymology other than that.
My edition of the concise OED says it is from the French rôle, derived from the French roule, rolle and then links to roll. Under roll it decribes the etymology as being derived from the Latin rotulus, diminutive of rota (wheel), via Old French rol(l)ler, rouler and ro(u)lle.
The circumflex in French represents a former letter that has dropped out. Almost always it was s. This is a rare example of a lost t with a circumflex as its memorial. French spelling is highly etymological; it was fixed in the 17th century by the Académie française to continue classical Latin spelling or to reflect 11th-century Old French pronunciation as closely as possible, even though pronunciation has changed drastically, making for a wide disconnect between pronunciation and spelling. At least the circumflex serves as a memorial to a lost letter, which is better than keeping the letter that isn’t pronounced any more.