Inexcusable
Inexcusable is a 2005 novel written by Chris Lynch in the young adult genre. Through first-person narration, it chronicles the life of high school senior Keir Sarafian. A sequel, Irreversible, was published on September 6, 2016.
Wikipedia
Inexcusable (adjective)
not excusable
Unexcusable (adjective)
inexcusable
Wiktionary
Inexcusable (adjective)
too bad to be justified or tolerated
“Matt’s behaviour was inexcusable”
Oxford Dictionary