1. to make something less effective or weaken its quality; to spoil or corrupt
Usage: formal
2. to make legally invalid or ineffective
Usage: legal

Examples

• The scandal vitiated his reputation in the community.
• Poor planning vitiated the effectiveness of the rescue mission.
• The discovery of new evidence vitiated the original contract.
• Corruption in the system vitiated the democratic process.
• The technical error vitiated the entire experiment.
• His bias vitiated his ability to judge the case fairly.