Source : Webster's Revised Unabridged Dictionary (1913)

Credibility \Cred`i*bil"i*ty\ (kr[e^]d`[i^]*b[i^]l"[i^]*t[y^]),
   n. [Cf. F. cr['e]dibilit['e].]
   The quality of being credible; credibleness; as, the
   credibility of facts; the credibility of witnesses.

Source : WordNet®

credibility
     n : the quality of being believable or trustworthy [syn: {credibleness},
          {believability}] [ant: {incredibility}]