1. to deny the existence or truth of something
2. to cancel out or make ineffective

Examples

• His poor performance negates all his previous achievements.
• The new evidence negates the defendant’s alibi.
• Taking aspirin negates the blood-thinning effects of the medication.
• Her smile negates any impression of anger.
• The rain negates our plans for a picnic.
• This discovery negates the old theory completely.
• His apology doesn’t negate the harm he caused.