1. gives evidence as a witness in a court of law
Usage: legal context
2. declares or affirms solemnly; bears witness to something

Examples

• The witness testifies that she saw the defendant at the scene.
• He testifies under oath about what happened that night.
• Her success testifies to years of hard work and dedication.
• The expert testifies about the safety of the new medication.
• The evidence testifies to his innocence.
• She testifies before Congress about climate change.
• His behavior testifies to his good character.