WordWeb Online

1. Establish or strengthen as with new evidence or facts
   - confirm, corroborate, sustain, substantiate, support
    
2. To declare or affirm solemnly and formally as true
   - verify, assert, avow, aver, swan, swear
    
3. Say yes to

Derived forms: affirming, affirmed, affirms

See also: affirmable, affirmation, affirmative, affirmer

Type of: declare

Antonym: negate

Encyclopedia: Affirm