castellum, i, n. dim. [castrum],
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.