attest in WordNet English dictionary

1. authenticate, affirm to be true, genuine, or correct, as in an official capacity
   "I attest this signature"
   attest 
   
2. provide evidence for; stand as proof of; show by one's behavior, attitude, or external attributes
   "His high fever attested to his illness"; "The buildings in Rome manifest a high level of architectural sophistication"; "This decision demonstrates his sense of fairness"
   attest  certify  manifest  demonstrate  evidence 
   
3. give testimony in a court of law
   testify  attest  take the stand  bear witness 
   
4. establish or verify the usage of
   "This word is not attested until 1993"
   attest