Ardor vs. Arduous — What's the Difference?

Intensity of emotion, especially strong desire, enthusiasm, or devotion.

Involving or requiring strenuous effort; difficult and tiring

Great warmth of feeling; fervor; passion.

Demanding great effort or labor; difficult

Spirit; enthusiasm; passion.

Testing severely the powers of endurance; strenuous

Intense heat.

Hard to traverse, climb, or surmount.

Heat, in a literal sense; as, the ardor of the sun's rays.

Needing or using up much energy; testing powers of endurance.

Warmth or heat of passion or affection; eagerness; zeal; as, he pursues study with ardor; the fought with ardor; martial ardor.

(obsolete) burning; ardent

Bright and effulgent spirits; seraphim.

Difficult or exhausting to traverse.

A feeling of strong eagerness (usually in favor of a person or cause);

Steep and lofty, in a literal sense; hard to climb.

Intense feeling of love

Attended with great labor, like the ascending of acclivities; difficult; laborious; as, an arduous employment, task, or enterprise.

Feelings of great warmth and intensity;

Characterized by toilsome effort to the point of exhaustion; especially physical effort;

Taxing to the utmost; testing powers of endurance;

Difficult to accomplish; demanding considerable mental effort and skill;