τετράδιον

τετράδιον — tetrádion

τετράδιον, τετραδιου, τό (τετράς, the number four), a quarternion (τό ἐκ τεσσάρων συνεστος, Suidas): τῶν στρατιωτῶν, a guard consisting of four soldiers (for among the Romans this was the usual number of the guard to which the custody of captives and prisons was intrusted; two soldiers were confined with the prisoner and two kept guard outside), Act 12:4, where the four quaternions mentioned were on guard one at a time during each of the four watches. (Philo in Flacc. § 13 i. e. Mang. edition vol. ii, p. 533, 25.)