affirm

Verb

• say yes to

• to declare or affirm solemnly and formally as true
  • Before God I swear I am innocent
    

• establish or strengthen as with new evidence or facts
  • his story confirmed my doubts
    
  • The evidence supports the defendant
    

Related words

• Synonyms: 
  verify , assert , avow , aver , swan , swear , confirm , corroborate , sustain , substantiate , support
• Antonyms: 
  negate , contradict