Scholae (Greek: Σχολαί) is a Latin word, literally meaning "schools" (from the singular schola, school or group) that was used in the late Roman Empire to signify a unit of Imperial Guards. The unit survived in the Byzantine Empire until the 12th century. Michel Rouche succinctly traced the word's development, especially in the West: "The term schola, which once referred to the imperial guard, came to be applied in turn to a train of warrior-servants who waited on the king, to the group of clergymen who waited on the bishop, to the monks of a monastery, and ultimately to a choral society; it did not mean 'school' before the ninth century."