Lewis & Short

substantīvus, a, um, adj. [substantia], self-existent, substantive (post-class.).

  1. I. In gen.: res, Tert. adv. Prax. 26; id. adv. Hermog. 26.
  2. II. In gram.: substantivum verbum, the substantive verb, i.e. sum (a transl. of the Gr. ὑπαρκτικόν), Prisc. p. 812 fin. P.