Isidore of Seville, writing in the 7th century, claimed that the Latin word Maurus was derived from the Greek mauron, μαύρον, which is the Greek word for black. Indeed, by the time Isidore of Seville came to write his Etymologies, the word Maurus or "Moor" had become an adjective in Latin, "for the Greeks call black, mauron". "In Isidore’s day, Moors were black by definition…"