xystus, i, m., or xystum, i, n., = ξυστός or ξυστόν. Among the Greeks, a covered portico or gallery, where the athletes exercised in winter, Vitr. 5, 11, 4; 6, 10, 5; Tert. Apol. 38.

— Among the Romans, an open colonnade or portico, or a walk planted with trees, etc., for recreation, conversation, philosophic discussion, etc., Cic. Att. 1, 8, 2; id. Brut. 3, 10; id. Ac. 2, 3, 9; Sen. Ira. 3, 18, 3; Plin. Ep. 2, 17, 17; 5, 6, 19; 9, 7, 4; 9, 36, 3; Suet. Aug. 72; Phaedr. 2, 5, 18.