WordWeb Online

1. Capable of being believed
   "credible information"; "completely credible testimony";
   - believable
    
2. (a common but incorrect usage where 'credulous' would be appropriate) credulous
   "she was not the...credible fool he expected"
    
3. Appearing to merit belief or acceptance
   "a credible witness"

See also: believability, convincing, credibility, credibleness, credulous, likely, plausible, presumptive, thinkable

Antonym: unbelievable

Encyclopedia: Credible