Lewis & Short

dē-cumbo, cŭbŭi, 3, v. n.

  1. I. To lie down, sc. in bed or on a couch, to recline at table, to lie ill, be confined by sickness (good prose), Cato R. R. 156, 4: super lectum, Suet. Ner. 48: in aureo lecto, id. Caes. 49: hospes me ad cenam vocat. Venio, decumbo, Plaut. Merc. 1, 1, 98; so of reclining at table (cf. accumbo), id. Curc. 2, 3, 72; id. Stich. 5, 1, 6; Ter. Ph. 2, 2, 28; Cic. Verr. 2, 3, 25: familia decubuit, Sen. Ep. 96, 1; Gell. 18, 10, 2: febricitans, Vulg. Marc. 1, 30.
  2. II. Of a vanquished gladiator, t. t., to fall, Cic. Tusc. 2, 17, 41; id. Phil. 3, 14, 35.