Unforgiving (adjective)

1. Not willing to forgive someone for a mistake or error they have made.
2. Not willing to forgive someone for wronging them in some way.

Origin:

Late 16th century: from un- (expressing negation) + forgiving.

Examples:

1. Her unforgiving attitude was preventing her from moving forward.
2. His unforgiving nature made it hard for him to have lasting relationships.
3. The unforgiving terrain made the journey treacherous.
4. The unforgiving environment made it impossible for the plants to grow.
5. The unforgiving judge handed down a harsh sentence.