Lewis & Short

naumăchĭa, ae, f., = ναυμαχία, the representation of a sea-fight, a mock seafight (pure Lat. navale proelium).

  1. I. Lit.: naumachiam commisit, Suet. Claud. 21: naumachiae spectaculum edere, id. Caes. 44: naumachiam exhibere, id. Ner. 12; Vell. 2, 56, 1; 2, 100, 2; Mart. Spect. 28, 12: voluptates naumachiae, Vopisc. Aur. 34, 6.
  2. II. Transf., a place where mock seafights were exhibited: edidit et navale proelium in veteri naumachia, Suet. Tib. 7; 72; id. Dom. 5.