What does ardor mean?
The definition of ardor
Ar”dor, n.
Etym: [L. ardor, fr. ardere to burn: cf. OF. ardor, ardur, F. ardeur.] [Spelt also ardour.]

1 Heat, in a literal sense; as, the ardor of the sun’s rays.
2 Warmth or heat of passion or affection; eagerness; zeal; as, he pursues study with ardor; the fought with ardor; martial ardor.
3 pl.
Bright and effulgent spirits; seraphim. [Thus used by Milton.]

Synonyms
— Fervor; warmth; eagerness. See Fervor.