Lewis & Short

2. ostentus, ūs, m. [ostendo].

  1. I. In gen., a showing, exhibiting, display (not in Cic. or Cæs.): corpora extra vallum abjecta ostentui, as a public spectacle, Tac. A. 1, 29: atrocitatis, Gell. 20, 1, 48.
  2. II. In partic.
    1. A. Show, parade, external appearance: nova jura Cappadociae dedit bstentui magis, quam mansura, Tac. H. 1, 78.
    2. B. A sign, proof: ut Jugurthae scelerum ostentui essem, Sall. J. 24, 9; also a pretence, a sign given to deceive, id. ib. 46, 6: ut ostentui esset, multum vitalis spiritūs egestum, as a proof that, Tac. A. 15, 64; cf.: ostentui clementiae suae, id. ib. 12, 14 fin.: ostentui habere, Vulg. Heb. 6, 11.