Meaning

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

noun excessive fervor to do something or accomplish some end

noun prompt willingness

originFrom 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.

Etymology from Wiktionary, CC BY-SA 3.0