Zest refers to an enjoyably exciting quality, or to keen enjoyment itself. In culinary use, zest refers to small pieces of the peel of a lemon, lime, orange, or other citrus fruit used as flavoring.

// His humor added zest to the presentation's admittedly dry material.

// The couple has a zest for travel and adventure.

// Lime zest adds a burst of brightness to the dessert's rich flavor.

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"In 1773, J.A.E. Groeze, a German pastor with a zest for microscopy, first identified the tardigrade.... Because tardigrades are micro-sacs of goo (albeit with mouths, rectums, and esophagi), they don’t fossilize. But three of their intact remains from deep time have been found—all in amber, spread out over nearly sixty years of painstaking searching between 1964 and 2022." — Daniel Lewis, Twelve Trees: The Deep Roots of Our Future, 2024

When life hands you lemons, the saying goes, make lemonade. The message of this zingy aphorism is to take situations that are metaphorically sour and make them sweeter. You could do this by squeezing entire lemons to restore some excitement and enjoyment to your life, but you could also just take a little of the zest. Zest of course, refers to tiny pieces of citrus rind that are used to brighten, or enhance, the flavor of food and beverages. English speakers adopted the French word zest (zeste in modern French) in the late 1600s with this meaning, but it didn’t take long for them to spice up their language with an additional sense referring to any quality that adds enjoyment to something in the same way that the zest of a citrus fruit adds flavor to food. Later they extended the word to gusto—that is, enthusiastic enjoyment—itself, whether it be gustatory or not.