(a.) Suitable or fit to be relied on; worthy of dependence or reliance; trustworthy.

absolute accurate adducible admissible apposite attestative attested attestive authentic authenticated balanced based on believable calculable certain circumstantial circumstantiated cogent colorable compelling conceivable conclusive confirmed conscientious convincing cool credible cumulative damning decisive dependable determinative documentary documented evidential evidentiary ex parte eye-witness factual fail-safe faithful faithworthy fast fiducial fiduciary final firm firm as Gibraltar firsthand founded on grounded on guaranteed harmless hearsay honest honorable imperturbable implicit in equilibrium incontrovertible incorruptible indicative indisputable inerrable inerrant infallible invincible inviolable invulnerable irrefutable irresistible material meaningful nuncupative overwhelming plausible predictable presumptive principled probative proven punctilious reputable responsible riskless safe secure significant solid sound stable staunch steadfast steady straight substantial suggestive sure surefire symptomatic telling tenable tested to be trusted tried tried and true TRUE trustable trusted trustworthy trusty undangerous unerring unexceptionable unfailing unfalse unflappable unflinching unhazardous unimpeachable unperfidious unperilous unprecarious unquestionable unrisky unshakable untreacherous unwavering valid validated verified warranteed weighty well-balanced well-founded well-grounded without nerves worthy of faith