Mr. Heathcliff, I believe, had not treated him physically ill; thanks to his fearless nature, which offered no temptation to that course of oppression: he had none of the timid susceptibility that would have given zest to ill-treatment, in Heathcliff s judgment.
There are no more uses of "zest" in the book.
Show samples from other sources
If you didn’t know her, you’d think her zest comes from malice.
Susan Ee -- Angelfall
Kit chose the stories she herself enjoyed most, and her reading had a zest and liveliness that enthralled the children.
Elizabeth George Speare -- The Witch of Blackbird Pond