Lewis & Short

ob-nītor, xus (rarely nīsus), 3 (inf. obnitier for obniti, Lucr. 4, 437), v. dep., to bear, press, push, struggle, or strive against any thing (mostly poet. and in post-Aug. prose; not in Cic. or Cæs.); constr. with the dat., acc., or absol.

  1. I. Lit.: taurus Arboris obnixus trunco, Verg. A. 12, 105: contra, id. ib. 5, 21: toto corpore obnitendum, Quint. 5, 13, 11: remi Obnixi crepuere, Verg. A. 5, 205: densis ales (Lachm. aquila hinc) pinnis obnixa volabat Vento, Enn. ap. Prob. Verg. E. 6, 31, p. 354 Lion. (Ann. v. 148 Vahl.): obnixi (al. obnisi) urgebant, Liv. 34, 46.
    In pass. signif.: obnixo genu scuto, set or pressed against, Nep. Chabr. 1, 2.
    Of things: navigia fractas obnitier undas, Lucr. 4, 437.
  2. II. Trop.
      1. 1. To strive against, to resist, oppose (class. only in Part.): stant obnisi, Liv. 7, 33, 12: cum saepe obnitens repugnasset, Vell. 2, 89, 5; 2, 123, 2: stant obnixa omnia contra, Verg. A. 10, 359: venti obnixi lacerant nubila, Stat. Th. 5, 366: adversis, Tac. A. 15, 11.
      2. 2. To strive, endeavor; with inf.: triumphum Pauli impedire obnitebantur, Vell. 1, 9, 6.
        Hence, obnixus (obnīsus), a, um, P. a., steadfast, firm, resolute: (velim) obnixos vos stabili gradu impetum hostium excipere, Liv. 6, 12: firmitas, Plin. 36, 15, 24, § 105: obnixus curam sub corde premebat, Verg. A. 4, 332.
        In neutr., adverb., resolutely, obstinately: obnixum. Pauline, taces, Aus. Ep. 25, 28.
        Hence, adv.: obnixē (obnīsē), lit., striving against; hence, in gen., with all one’s strength, with might and main, strenuously, obstinately: obnixe omnia Facere, Ter. And. 1, 1, 134: oboedire, Liv. 4, 26, 12 (dub.; Weissenb. enixe): petere, Sen. Ep. 95, 1 (Haase, enixe; v. Krebs, Antibarb. p. 781).
        Comp.: argumentari, Claud. Mam. Stat. Anim. 1, 3.