noun
ardor
AR-der/ˈɑrdər/
Strong enthusiasm or passion.
The violinist plays with ardor, absorbed in each energetic stroke of the bow.

Etymology
Latin ardor named both physical heat and the heat of strong feelings. The modern sense preserves that image of passion or devotion as something that burns intensely.
In context
with all my ardor I was capable of a more intense application and was more deeply smitten with the thirst for knowledge
More examples
- Their ardor for the project survived several setbacks.
- She pursued the cause with tireless ardor.
- The disappointing result did little to cool his ardor.