Lewis & Short

subsĭdĭārĭus, a, um, adj. [subsidium]; in milit. lang., of or belonging to a reserve, reserve-, subsidiary.

  1. I. Lit.
    1. A. Adj. (class.): cohortes, Caes. B. C. 1, 83; Liv. 9, 27; Tac. A. 1, 63: acies, Auct. B. Afr. 59, 2: naves, Auct. B. Alex. 14, 3.
    2. B. Subst.: subsĭdĭ-ārĭi, ōrum, m., the reserve, body of reserve, Liv. 5, 38; 6, 8; 9, 32.
  2. II. Transf., in gen., out of the military sphere, serving for support, subsidiary: palmes, = resex, Col. 4, 24, 13 and 16.
    1. B. Esp.: actio, jurid. t. t., a form of action by which the ward seeks compensation from the magistrate who has given him an improper guardian, Dig. 27, 8, 1 pr.; cf. Cod. Just. 5, 75, 1 and 5.
      Hence, adverb.: subsidiaria agere, to institute such an action, Dig. 27, 8, 1, § 4.