Lewis & Short

obses (old orthogr. opses, in the first Epit. of the Scipios; v. infra; Inscr. Spec. Epigr. p. 5, 11 Jahn), ĭdis (gen. plur. obsidium, Caes. B. G. 5, 27; 6, 9; Liv. 2, 13, 97), m. and f. [ob-sedeo].

  1. I. Lit., a hostage: OPSIDES ABDOVCIT, first Epit. of the Scipios: ut obsides accipere, non dare consueverint, Caes. B. G. 1, 14; Liv. 34, 35: obsides alicui imperare, Cic. Imp. Pomp. 12, 35: dedere, Sall. J. 54, 6: retinere aliquem obsidem, as a hostage, Nep. Them. 7, 2.
    Fem.: me tamen acceptā poterat deponere bellum Obside, Ov. M. 8, 48: obsides, qui Porsenae mittebantur, Plin. 34, 6, 13, § 29: inter se dare, to exchange, Caes. B. G. 1, 9.
  2. II. Transf., in gen., a surety, security, bail, pledge (syn.: sponsor, vindex, vas, praes): Phocion se ejus rei obsidem fore, pollicitus est, to be surety, to answer for it, Nep. Phoc. 2, 4: accipere aliquem obsidem nuptiarum, Cic. Clu. 66, 188: conjugii, Ov. H. 2, 34: rei, Nep. Phoc. 2, 4: dare obsides, with a foll. acc. and inf., to give a surety or guarantee: tantum modo oratoribus Metellus obsides non dedit, se nullā in re Verri similem futurum, Cic. Verr. 2, 3, 53, § 124.
    Also of inanim. subjects: habemus a C. Caesare sententiam tamquam obsidem perpetuae in rem publicam voluntatis, Cic. Cat. 4, 5, 9; id. Cael. 32, 78; id. Clu. 30, 83; Quint. 12, 7, 3: obsidem enim se animum ejus habere, Liv. 39, 47.