1 attest (to sth) to show that sth is true 证明，表明（某事是真的）: Her long fight against cancer attested to her courage. 她长期跟癌症作斗争，这证明了她的勇气。

2 to state that you believe that sth is true or genuine, for example in a court of law 为某事物的真实性作证（比如在法庭上）: The signature was attested by two witnesses. 有两名证人证明这签名是真的。