to say publicly, especially in a law court, that something is true or that it happened(尤指在法庭上)作证,证明…是真实的
A handwriting expert witnessed to the authenticity of the letter.笔迹专家证明了这封信不是伪造的。
[ + -ing verb ] She witnessed to having seen the robbery take place.她作证说目睹了抢劫的过程。