Lewis & Short

subdĭtīvus, a, um, adj. [subdo], substituted, supposititious, spurious, counterfeit (rare but class.): de illo subditivo Sosia mirum nimis est, Plaut. Am. 2, 2, 198; 1, 2, 35: archipirata, Cic. Verr. 2, 5, 27, § 69: fratrem ut subditivum arguere, Suet. Ner. 7.
Subst.: Subdĭtīvus, i, m., the title of a comedy of Cœcilius, Gell. 15, 9, 1 (Com. Rel. p. 39 sq. Rib.).