Ardor, n.
Etymology: [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.
2 more senses
Bright and effulgent spirits; seraphim. [Thus used by Milton.]
Syn. -- Fervor; warmth; eagerness. See Fervor.
Shades of meaning
Fernald has no entry of its own for ardor; he lists it under enthusiasm.
He lists it without comment; the entries above explain its neighbors.