Lewis & Short

Circēii, ōrum (abl. Circēis, Hor. S. 2, 4, 33 K. and H.), m., = Κιρκαῖον,

  1. I. the town of Circeii, near the promontory of the same name, in Latium; acc to the fable, named after Circe, who fled hither from Colchis (cf. the preced. art.), now Circello, Mel. 2, 4, 9; Plin. 3, 5, 9, § 56 sq.; Cic. Att. 15, 10 fin.; Liv. 1, 56, 3; distinguished for its excellent oysters, Hor S. 2, 4, 33 Heind.
    Hence,
  2. II. Circēiensis, e, adj., of Circeii: ostreae, Plin. 32, 6, 21, § 62.
    In plur.: Circēienses, lum, m., the inhabitants of Circeii, Cic. N D 3, 19, 48; Liv 6, 17, 7.