The word "unforgivable" means something that is so bad or wrong, it cannot be forgiven. It refers to an action or behavior that is considered to be inexcusable and deserving of no mercy or pardon. The term can also describe a person who has committed such an offense, making them unworthy of being forgiven. In essence, the word "unforgivable" conveys the idea of something that is so severe, it goes beyond the limits of forgiveness and reconciliation.