zeal

Etymology

From Middle English zele, from Old French zel, from Late Latin zēlus, from Ancient Greek ζῆλος (zêlos, “zeal, jealousy”), from Proto-Indo-European *yeh₂- (“to search”). Related to jealous.

noun

1. The fervour or tireless devotion for a person, cause, or ideal and determination in its furtherance; diligent enthusiasm; powerful interest.
   She extols the virtues of veganism with missionary zeal.
   […] the highest zeal in religion and the deepest hypocrisy, so far from being inconsistent, are often or commonly united in the same individual character. 1779, David Hume, Dialogues Concerning Natural Religion, part 12, pages 143–144
   The stockman’s zeal for eliminating the coyote has resulted in plagues of field mice, which the coyote formerly controlled. 1962, Rachel Carson, chapter 15, in Silent Spring, Boston: Houghton Mifflin, page 248
2. (obsolete) A person who exhibits such fervour or tireless devotion.
   […] like a malicious purblinde zeale as thou art! 1614, Ben Jonson, Bartholomew Fair, London: Robert Allot, act v, scene 5, page 85
   […] there are questionlesse both in Greeke, Roman and Africa Churches, solemnities, and ceremonies, whereof the wiser zeales doe make a Christian use, and stand condemned by us; 1642, Thomas Browne, Religio Medici, London: Andrew Crooke, page 5
3. The collective noun for a group of zebras.
   A zeal of zebras confuses predators. Each zebra has a different set of stripes. 2012, Alex Kuskowski, Zeal of Zebras: Animal Groups on an African Safari, page 8