I.a castle, fort, citadel, fortress, stronghold, Sisenn. ap. Non. p. 514, 7; Caes. B. G. 2, 30; id. B. C. 3, 36; Cic. Phil. 5, 4, 9; id. Caecin. 7, 20; Sall. J. 54, 6; Nep. Milt. 2, 1; id. Alcib. 7, 4; Liv. 10, 46, 11; 21, 11, 10; Verg. A. 5, 440; Hor. Ep. 2, 2, 34 al.; also of a single bulwark, bastion, Caes. B. G. 1, 8; 2, 8; 7, 69; id. B. C. 3, 44; and poet. of a dwelling in an elevated position, Verg. G. 3, 475.—
B. In mechanics, a structure in which the water of an aqueduct is collected, to be distributed by pipes or channels in different directions, a reservoir, Vitr. 8, 6; Plin. 36, 15, 24, § 121; Front. Aquaed. 35; Dig. 19, 1, 17; 43, 20, 1; Inscr. Orell. 3203 al.—
II. Trop., shelter, stronghold, defence, refuge (cf. arx, I. B.): “templum Castoris fuit arx civium perditorum... castellum forensis latrocinii,” Cic. Pis. 5, 11: “urbem philosophiae, mihi crede, proditis, dum castella defendis,” id. Div. 2, 16, 37: “tribunal Appii castellum omnium scelerum,” Liv. 3, 57, 2.
