credibility
    n 1: the quality of being believable or trustworthy [syn:
         credibility, credibleness, believability] [ant:
         incredibility, incredibleness]

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.
   [1913 Webster]

CREDIBILITY. Worthiness of belief. To entitle a witness to credibility, he 
must be competent. Vide Competency. 
     2. Human testimony can seldom acquire the certainty of demonstration. 
Witnesses not unfrequently are mistaken or wish to deceive; the most that 
can be expected is that moral certainty which arises from analogy. The 
credibility which is attached to such testimony, arises. from the double 
presumption that the witnesses have good sense and intelligence, and that 
they are not mistaken nor deceived; they are further presumed to have 
probity, and that they do not wish to deceive. 
     3. To gain credibility, we must be assured, first, that the witness has 
not been mistaken nor deceived. To be assured as far as possible on this 
subject, it is proper to consider the nature and quality of the facts 
proved; the quality and person of the witness; the testimony in itself; and 
to compare it with the depositions of other witnesses on the subject, and 
with known facts. Secondly, we must be satisfied that he does not wish to 
deceive: there are strong assurances of this, when the witness is under 
oath, is a man of integrity, and disinterested. Vide Arch. Civ. Pl. 444; 5 
Com. Dig. 449; 8 Watts, R. 227; Competency.