Lewis & Short

† lēthargĭcus, a, um, adj., = ληθαργικός,

  1. I. drowsy, lethargic: morbus, Plin. 23, 1, 6, § 10: somnus, Aug. Ep. 48 ad Vincent.; Cael. Aur. Acut. 1, 3, 38 al.
  2. II. Subst.: lē-thargĭcus, i, m., one affected with lethargy, a lethargic person: ut lethargicus hic cum fit pugil et medicum urget, Hor. S. 2, 3, 30; Plin. 24, 6, 16, § 25: lethargicos excitare labor est, id. 26, 11, 72, § 118.