Lewis & Short

ardor, ōris, m. [ardeo], a flame, fire, heat, burning heat, lit. and trop.

  1. I. Lit.: solis ardor, Lucr. 2, 212: exortus est sol cum ardore, Vulg. Jac. 1, 11: ignium, Lucr. 5, 587: ignis, Vulg. 2 Pet. 3, 12: flammarum, Lucr. 5, 1093: flammaï, id. 5, 1099 al.: visas ab occidente faces ardoremque caeli, Cic. Cat. 3, 8: ardor caelestis, qui aether vel caelum nominatur, id. N. D. 2, 15, 41: ardore deflagrare, id. Ac. 2, 37, 119: ardores corporum in morbis, Plin. 14, 16, 18, § 99: Visitabo vos in egestate et ardore, with burning fever, Vulg. Lev. 26, 16 al.
  2. II. Trop.
    1. A. Of the flashing fire of the eyes, brightness, brilliancy: fervescit et ex oculis micat acribus ardor, and fire gleams forth from the keen eyes, Lucr. 3, 289: ille imperatorius ardor oculorum, Cic. Balb. 21, and id. N. D. 2, 42, 107.
      Of the external appearance in gen.: in te ardor voltuum atque motuum, Cic. Div. 1, 37, 80: oris, animation, Vell. 2, 35.
    2. B. Of the passions or feelings, heat, ardor, glow, impatience, eagerness, ardent desire: Sive voluptas est sive est contrarius ardor, i. e. dolor, some tormenting pain, Lucr. 3, 251: cupiditatum ardore restincto, Cic. Fin. 1, 13, 43: ardor mentis ad gloriam, id. Cael. 31: quem ardorem studii censetis fuisse in Archimede, qui etc., id. Fin. 5, 19, 50: ardor animi non semper adest, isque cum consedit, id. Brut. 24, 93: vultus ardore animi micans, Liv. 6, 13: ardorem compescere, Tac. Agr. 8; Liv. 8, 16.
      Transf. from the combatants to the weapons: tantus fuit ardor armorum, Liv. 22, 5: Ardorem cupiens dissimulare meum, glowing love, Tib. 4, 12, 6; so Ov. M. 7, 76.
      With obj. gen.: at te ejusdem virginis ardor Perdiderat, Ov. M. 9, 101; 9, 140; Hor. Epod. 11, 27 al.
      And meton., the object of ardent affection, love, flame: tu primus et ultimus illi Ardor eris, Ov. M. 14, 683.