I.a siege, investment, blockade (mostly ante-class. and post-Aug. for obsidio; not in Cic. or Cæs.; but cf. obsidio).
I. Lit.: “obsidium dictum ab obsidendo, quominus hostis egredi posset inde,” Varr. L. L. 5, § 90 Müll.: obsidium, tam quam praesidium, subsidium, recte dicitur, Paul. ex Fest. p. 193 Müll.: saevo obsidio premere aliquem, Enn. ap. Non. 216, 29 (Ann. v. 28 Vahl.): “obsidium facere Ilio,” Plaut. Bacch. 4, 9, 24: “obsidio circumdare,” Tac. A. 13, 41: “obsidium urgere,” id. H. 4, 28; Flor. 4, 4, 4; Gell. 15, 31, 1; Amm. 20, 7, 3: “ad liberandum Mogontiaci obsidium,” Tac. H. 4, 37.—
II. Trop.
A. A waylaying, an ambush: “obsidia hominum aut insidiosorum animalium,” Col. 8, 2, 7.—
B. Attention, foresight: “curatoris,” Col. 9, 9, 1; cf. obsidio.—
C. Danger: “tuo tergo obsidium adesse,” Plaut. Mil. 2, 2, 64.