Lewis & Short

aggressĭo (adg-), ōnis, f. [aggredior].

  1. I. A going to or toward a thing (very rare; in the class. per. only in rhet. lang. for a proëm, introduction to a speech, = prooemium): cumque animos primā adgressione occupaverit, infirmabit excludetque contraria, * Cic. Or. 15, 50.
    Also a rhetorical syllogism, Gr. ἐπιχείρημα, Quint. 5, 10, 4; 28, 14, 27.
  2. II. An attack, assault (cf. aggredior, II. B.), App. M. 8, p. 208, 27 Elm.