Lewis & Short

Orcus, i, m. [kindr. with ἕρκος and the Lat. urgeo: Orcum quem dicimus, ait Verrius ab antiquis dictum uragum, Fest. p. 202 Müll.
Hence, prop., that which impels, constrains, confines].

  1. I. the Lower World, the abode of the dead, Orcus: Acherunsia templa alta Orci, salvete infera, Enn. ap. Varr. L. L. 7, § 6 Müll. (Trag. v. 107 Vahl.); Lucr. 1, 115; 6, 762: Minos sedet arbiter Orci, Prop. 4, 18, 27; Verg. A. 6, 273.
  2. II. Transf.
    1. A. The god of the infernal regions, Orcus, Pluto: Orcus recipere ad se hanc noluit, Plaut. Ps. 3, 2, 6: bene vale, apud Orcum te videbo, id. As. 3, 3, 16: ut Verres alter Orcus, venisse Ennam, etc., Cic. Verr. 2, 4, 50, § 111: pallidus, Verg. G. 1, 277.
    2. B. Death (mostly poet.): horriferis accibant vocibus Orcum, Lucr. 5, 996; Hor. Ep. 2, 2, 178: Orcum morari, to hesitate to die, id. C. 3, 27, 50: rapacis Orci fine destinatā, id. ib. 2, 18, 30: cum Orco rationem habere, to risk one’s life, Varr. R. R. 1, 4: janua haec Orci, Plaut. Bacch. 3, 1, 1.