Lewis & Short

2. Rēgillus, i, m.

  1. I. A town of the Sabines, whence Appius Claudius emigrated to Rome, Liv. 2, 16 Drak.; also called Rēgilli, ōrum, m., Suet. Tib. 1.
    Hence, Rēgillānus, a, um, and Rēgillensis, e, adj., of or belonging to Regillus: Claudius Appius Regillanus, Suet. Tib. 2: Claudius Regillensis, Liv. 8, 15.
  2. II. A small lake in Latium (the mod. Cornufelle), celebrated for the victory over the Latins gained there by the Romans under the dictator Postumius, Cic. N. D. 3, 5, 11; called also lacus Regillus, Liv. 2, 19; Plin. 33, 2, 11, § 38; and Regilli lacus, Flor. 1, 11, 2; Aur. Vict. Vir. Ill. 16.
    Hence, Rēgillensis, surname of the Postumii: M. Postumio Regillensi, Liv. 4, 49, 7: A. et L. Postumii Regillenses, id. 6, 22, 5.
  3. III. A Roman surname in the Æmilian gens, Cic. Att. 12, 24, 2: M. Aemilius Regillus, Liv. 24, 7 fin.; 8; 29, 11 fin.; 38.