Lewis & Short

1. rĕpugnantĭa, ae, f. [repugno].

  1. * I. A resistance, opposition; concr.: (natura) hanc dedit repugnantiam apibus (sc. cuspidem), a means of defence, Plin. 21, 13, 45, § 78.
  2. II. A contradiction, contrariety, incompatibility, repugnance: rerum, Cic. Phil. 2, 8, 19: utilitatis, id. Off. 3, 4, 17: naturae (opp. concordiae), Plin. 22, 23, 49, § 106: repugnantiam inducere, Cic. Off. 3, 7, 34.