An abolla was a cloak-like garment worn by ancient Greeks and Romans. Nonius Marcellus quotes a passage of Varro to show that it was a garment worn by soldiers (vestis militaris), and thus opposed to the toga.
The abolla was, however, not confined to military occasions, but was also worn in the city. It was especially used by the Stoic philosophers at Rome as the pallium philosophicum, just as the Greek philosophers were accustomed to distinguish themselves by a particular dress. Hence, the expression of Juvenal facinus majoris abollae merely signifies, "a crime committed by a very deep philosopher".
The term abolla is actually a Latinization of the Greek ambolla (ἀμβόλλα) or anabole (ἀναβολή), for a loose woolen cloak.