Peristylium, peristylij, vel peristylum, peristyli, pen. corr. Cic.A place set about with pillers: a cloyster: a long entrie in an house.
Lewis and Short: Latin dictionary
pĕristlĭum, ii, n., = peristu/lion, a place surrounded with columns on the inside, a peristyle, Vitr. 3, 1; 5, 11; Plin. Ep. 10, 70, 3; 10, 71, 1; Suet. Aug. 82; cf. peristylum.