Lewis & Short

1. stagno, āvi, ātum, 1, v. n. and a. [id.].

  1. I. Neutr.
    1. A. Lit., to form a pool of standing water, to stagnate, be stagnant (mostly poet. and in post-Aug. prose; not in Cic.; cf. redundo): stagnans Nilus, Verg. G. 4, 288: ubi mollius solum reperit (Indus) stagnat insulasque molitur, Curt. 8, 9, 7: nam flumen, quo latius fusum est, hoc placidius stagnat, id. 9, 2, 17: aquae stagnantes, id. 8, 13, 9: stagnantibus undis, Sil. 5, 95: Nili aquae, ubi evagatae stagnant, Plin. 13, 11, 22, § 71; 31, 3, 21, § 31: stagnante Pado, Luc. 4, 134.
    2. B. Transf., of places which lie under water, to be overflowed or inundated: moenia oppidi stagnabant redundantibus cloacis, Sall. Fragm. ap. Non. 138, 7: paludibus orbis, Ov. M. 1, 324: ripae, Sil. 10, 89: terra caede, id. 6, 36: solum, Plin. 17, 26, 40, § 249: regna sanguine, Sil. 12, 43.
      Subst.: stagnantĭa, ium, n., inundated places: terrae motus fervens in umidis, fluctuans in stagnantibus, Plin. 2, 80, 82, § 193.
  2. II. Act.
    1. A. Lit., to cause to stand, to make stagnant: quo (bitumine) aqua omnis (Maris Mortui) stagnatur, Just. 36, 3, 7: Cecropio stagnata luto, Stat. S. 3, 20, 110.
    2. B. Transf., to cover with water, to overflow, inundate a place: Tiberis plana Urbis stagnaverat, Tac. A. 1, 76: (loca) stagnata paludibus ument, Ov. M. 15, 269; Col. poët. 10, 11.