I.there, that way (ante-class. and very rare): “exi istac per hortum,” Plaut. Ep. 5, 1, 53; so id. Pers. 3, 3, 39; Ter. Heaut. 3, 3, 27.—
II. Trop. ( = eo modo), in that way, in such wise: nequaquam istuc istac ibit: magna inest certatio, Enn. ap. Cic. N. D. 3, 25 fin. (Trag. v. 304 Vahl.): “istac indico,” on this side, Plaut. Trin. 2, 2, 101.