Lewis & Short

pĕrendĭē, adv. [Gr. πέραν-dies], on the day after to-morrow (class.): cras agito, perendie agito, Plaut. Merc. 2, 3, 41; id. Aul. 2, 1, 34; id. Stich. 4, 1, 12: scies igitur fortasse cras, summum perendie, Cic. Att. 12, 44, 3; id. Fam. 16, 17, 3.