Lewis & Short

dēmonstrātīvus, a, um, adj. [demonstro], pointing out, designating.

  1. I. In gen. (very rarely): digitus, the indexfinger, forefinger, Cael. Aur. Tard. 5, 1, 21.
  2. II. In rhetor., demonstrative, = ἐγκωμιαστικόν: genus (orationis), a branch of rhetoric employed in praising or censuring, i. e. laudatory or vituperative (usuually the former), Cic. Inv. 1, 5, 7; Quint. 3, 4, 14; 2, 10, 11: causa, Cic. Inv. 2, 4: materia, Quint. 3, 8, 53; 11, 1, 48: pars orationis, id. 2, 21, 23; cf. 7, 4, 2.
    1. B. Subst.: dēmonstrātīva, ae, f., demonstrative kind of oratory, Quint. 3, 8, 63 sq.; 3, 8, 8.
      * Adv.: dēmonstrātīvē, demonstratively, Macr. Somn. Scip. 2, 16.