Lewis & Short

Lĕmŭres, um, m., shades, ghosts of the departed.

  1. I. Lit.: Lemures animas dixere silentum, Ov. F. 5, 483.
    1. B. Transf., in gen., ghosts, spectres: lemures larvae nocturnae et terrificationes imaginum et bestiarum, Non. 135, 15 sq.: somnia, terrores magicos, miracula, sagas, Nocturnos lemures portentaque Thessala rides, Hor. Ep. 2, 2, 209: tunc nigri lemures ovoque pericula rupto, Pers. 5, 185.
      Hence,
  2. II. Lĕmū-rĭa, ōrum, n., a festival held on the 9th, 11th, and 13th of May to appease the ghosts of the departed: nocturna, Ov. F. 5, 421 sq.