Lewis & Short

ex-cŭbo, bŭi, bĭtum, 1, v. n., to lie or sleep out of doors.

  1. I. In gen. (rare but class.): moniti Lacedaemonii, ut urbem et tecta linquerent armatique in agro excubarent, Cic. Div. 1, 50, 112: apes noctu deprehensae in expeditione excubant supinae, Plin. 11, 8, 8, § 19.
    1. B. Trop.: Graeciam alienis sedibus, Just. 8, 4, 7, v. Fittbogen ad h. l.
      Far more freq.,
  2. II. In partic., to lie out on guard, to keep watch, to watch.
    1. A. Lit.: duae semper legiones pro castris excubabant, Caes. B. G. 7, 24, 5: legiones in armis, id. ib. 7, 11, 6: legiones ad mare, id. B. C. 3, 63, 6: cohortes ad munitionem, id. ib. 3, 50, 1: legio per muros, Verg. A. 9, 175: excubitum in porta cohortes mittere, Sall. J. 100, 4: Cerberus excubat ante fores, Tib. 1, 3, 72: quae (naves) ad portum excubabant, kept watch, Caes. B. C. 2, 22, 3 et saep.
      Poet.: (Cupido Chiae) Pulchris excubat in genis, sits on the watch, lurks, Hor. C. 4, 13, 8.
      Of things as subjects: alni contra erumpentium amnium impetus riparum muro in tutela ruris excubant, Plin. 16, 37, 67, § 173: laurus ante limina excubat, id. 15, 30, 39, § 127.
    2. B. Trop., to watch, be watchful or vigilant, to be on the alert: cum Caesar ad opus consuetudine excubaret, etc., Caes. B. G. 7, 24, 2: in navibus, id. B. C. 3, 8 fin.: excubabo vigilaboque pro vobis, Cic. Phil. 6, 7, 18: sapiens semper animo sic excubat, ut nihil ei improvisum accidere possit, id. Tusc. 4, 17, 37: curam rei publicae summae defendundae jam pridem apud vos excubare, is watchful, active, Planc. ap. Cic. Fam. 10, 8, 5: omnis eorum ars urbibus excubabat, i. e. was concerned, labored for the cities, Plin. 35, 10, 37, § 118.
      Pass. impers.: rerum, non animi pretiis excubatur, care is exercised, Plin. 35, 7, 32, § 50.