Lewis & Short

inter-dum, adv.,

  1. I. sometimes, occasionally, now and then, = nonnumquam: interdum fio Juppiter, quando lubet, Plaut. Am. 3, 1, 4: interdum cursus est in oratione incitatior, interdum moderata ingressio, Cic. Or. 59: modo-interdum, Suet. Calig. 43: modo-modo-interdum, id. Ner. 49.
  2. II. I. q. per aliquod tempus, for some time (post-Aug.): acribus custodiis domum et vias saepserat Livia; laetique interdum nuntii vulgabantur, donec, Tac. A. 1, 5: occulere interdum et terrae mandare parabat, Sil. 6, 30; id. 4, 490.
  3. III. I. q. interea, interim, meanwhile, in the meantime (post-class.): interdum cognito strepitu procurrit cubiculo, App. M. 9, p. 226, 17; 4, p. 149, 14; Dig. 4, 8, 16, § 1; Cod. Th. 4, 3, 1.