(a.) Tainted with, or full of, sin; wicked; iniquitous; criminal; unholy; as, sinful men; sinful thoughts.

aberrant abnormal abominable amiss arrant atrocious bad base black blamable blameful blameworthy censurable corrupt criminal culpable damnable dark delinquent demonic depraved deviant disgraceful evil evildoing execrable felonious flagitious flagrant foul godless guilty hardly the thing heinous ignominious ill illegal immoral impious improper inaccurate inappropriate inauspicious incorrect indecorous inexpedient infamous inferior iniquitous invalid irreligious irreverent knavish low malefactory malevolent malfeasant monstrous naughty nefarious not done not the thing off-base off-color out-of-line peccant profane profligate rank reprehensible reprobate sacrilegious scandalous shameful shameless sinister terrible un-Christly unangelic unchristian undue unfavorable unfit unfitting unforgivable ungodly unhealthy unholy unkind unlawful unpardonable unpleasant unrighteous unsaintly unseemly unskillful unspeakable unsuitable untoward unworthy vicious vile villainous wicked wrong wrongdoing wrongful