From The Collaborative International Dictionary of English v.0.48 [gcide]:
Ardor \Ar"dor\, n. [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.
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2. Warmth or heat of passion or affection; eagerness; zeal;
as, he pursues study with ardor; the fought with ardor;
martial ardor.
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3. pl. Bright and effulgent spirits; seraphim. [Thus used by
Milton.]
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Syn: Fervor; warmth; eagerness. See Fervor.
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From WordNet (r) 3.0 (2006) [wn]:
ardor
n 1: a feeling of strong eagerness (usually in favor of a person
or cause); "they were imbued with a revolutionary ardor";
"he felt a kind of religious zeal" [syn: ardor, ardour,
elan, zeal]
2: intense feeling of love [syn: ardor, ardour]
3: feelings of great warmth and intensity; "he spoke with great
ardor" [syn: ardor, ardour, fervor, fervour,
fervency, fire, fervidness]