Lewis & Short

2. excursus, ūs, m. [excurro], a running out or forth (rare; not in Cic.; cf. excursio).

  1. I. Lit.: excursusque breves tentant (apes), excursions, Verg. G. 4, 194: avium, Sol. 20, 3; cf. the outflow of water, Plin. Ep. 4, 30, 8.
      1. 2. In partic., in milit. lang. (like excursio, I. B.), a sally, charge, onset, attack; an inroad, invasion: excursus militum, * Caes. B. C. 3, 92, 2: rari, Tac. G. 30: subiti, id. Agr. 20: navigiorum, Auct. B. Alex. 19, 2.
    1. B. Transf., of localities, a projecting, projection: promontorium vasto excursu, Plin. 6, 2, 2, § 6: ad Pyrenaei montis excursum, id. 4, 17, 31, § 105.
  2. II. Trop., a digression in speaking: hae (egressiones) per totam causam varios habent excursus, ut laus hominum locorumque, etc., Quint. 4, 3, 12; opp. opus ipsum, Plin. Ep. 5, 6, 43.