The word 'zesty' is a relatively modern English formation, built upon the noun 'zest'. 'Zest' entered English in the 17th century from French 'zeste', referring specifically to the outer, flavorful peel of citrus fruits. The ultimate origin of 'zeste' is obscure but may be imitative, perhaps of the sound of scraping the peel. The figurative sense of 'zest' as "keen enjoyment" or "gusto" developed in the 18th century, likening the invigorating quality of life to the tangy flavor of citrus peel. By adding the productive adjectival suffix '-y', English created 'zesty' to describe anything possessing the lively, pungent quality—whether literal flavor or metaphorical vigor—inherent in its root.

Structure: zest (spicy peel, enthusiasm) + y (adjective-forming suffix) zest: From French 'zeste' (orange or lemon peel), of uncertain origin, possibly imitative. In this word, it functions as the core root conveying the sense of piquancy or liveliness. y: A native English suffix (from Old English '-ig', Proto-Germanic '-īgaz', PIE '-kos') used to form adjectives meaning "characterized by; full of".