...serve him with zeal, and love him with fidelity.
-- Fanny Burney, Cecilia: Or, Memoirs of an Heiress
This passionate profession, which Newman uttered with the greater zeal that it was the first time he had felt the relief words at once as hard and as careful as hammer-taps could give his spirit, kindled two small sparks in Mrs. Bread's fixed eyes.
-- Henry James, The American
Zeal is derived from the Greek word zelos, the same root as the word zealous.