the word "zest" entered english in the 17th century from the french term "zeste," which referred to a piece of lemon or orange peel used to flavor drinks. the french word likely originated from a latin term, "scistus," meaning "split" or "divided," which itself derives from the verb "scindere" (to split). this connection to "splitting" or "peeling" is the literal origin of the culinary sense. the figurative meaning of "keen enjoyment" or "enthusiasm" developed later in english, metaphorically transferring the idea of something that adds a piquant flavor or excitement to an experience.

the word is a simplex loanword from french. it does not contain separable morphemes within its modern english spelling.