Emily Dickinson Lexicon

ZEST, n. [Pers. زِسَتَنْ zistan, to peel. Class Sd.]

1. A piece of orange or lemon peel, used to give flavor to liquor; or the fine thin oil that spurts out of it when squeezed; also, the woody thick skin quartering the kernel of a walnut. – Cyc.
2. Relish; something that gives a pleasant taste; or the taste itself.