1. not willing to forgive others for their mistakes or wrongdoings
2. having conditions that make mistakes very costly or difficult to recover from

Examples

• She remained unforgiving toward her brother who had betrayed her trust.
• The judge was unforgiving in his sentencing of repeat offenders.
• Mountain climbing can be an unforgiving sport where small errors prove fatal.
• The desert environment is unforgiving to travelers without proper supplies.
• His unforgiving attitude made it difficult for him to maintain friendships.
• The unforgiving deadline left no room for delays or mistakes.
• Professional sports can be unforgiving to athletes who suffer serious injuries.