Lewis & Short

nixor, āri, dep. n. [1. nitor], to lean or rest upon; to strive, endeavor (poet.).

  1. I. Lit., Lucr. 6, 836; 3, 1001: pars vulnere clauda retentat Nixantem (serpentem), Verg. A. 5, 279 Wagner N. cr.
  2. II. Trop., to depend upon: fundamenta, quibus nixatur vita salusque, Lucr. 4, 506.