1. giving evidence or making a statement under oath in a court of law
Usage: legal context
2. declaring or affirming something publicly or formally
3. serving as evidence or proof of something

Examples

• The witness is testifying about what she saw that night.
• He spent three hours testifying before the grand jury.
• The documents are testifying to the company’s financial problems.
• She was nervous about testifying in front of so many people.
• The expert is testifying about the safety of the new drug.
• His success is testifying to years of hard work.
• The defendant will be testifying on his own behalf tomorrow.