Definition of zest:

part of speech: noun

Something that gives a flavor; relish.

Usage examples :

• " How full of zest life becomes in the country," cried Amy, " if one only goes to work in the right way!" "Nature's Serial Story", - E. P. Roe

• Fortune, accident, would have taken from us the great zest of life, which is desire. "Lucretia, Complete", - Edward Bulwer-Lytton