The outer skin of a citrus fruit, used as a flavouring or garnish. (noun)
To scrape the zest from a fruit (verb)
To make more zesty (verb)
Examples of word zest
The soft, white part of the peel just underneath the zest is the pith.
The zest is the colorful outer layer of the citrus peel.
The pith can actually give your baked good a bitter or slightly unpleasant taste if you incorporate it into a recipe (there are some recipes that call for using a whole fruit, but those usually compensate with extra sugar), so it is important to remove only the zest from the citrus rind when you are using it.
The zest can be removed very carefully with a sharp pairing knife, but the easiest and best way to remove the zest is with a microplane.
The reason that the zest is so desireable is that it contains lots of essential oils that make for a strong, pleasant flavor.