1. (n.) Failing in duty; offending by neglect of duty.

2. (n.) One who fails or neglects to perform his duty; an offender or transgressor; one who commits a fault or a crime; a culprit.

aberrant abnormal abominable atrocious bad person behindhand careless criminal crook culprit deceiver defaulter defaulting derelict deviant disgraceful disregardful evil evil man evil person evildoer failing felon gangster hardly the thing hooligan ignominious illegal improper in arrear in arrears inappropriate incorrect indecorous infamous late lawbreaker lax levanter malefactor malevolent malfeasant malfeasor miscreant misdemeanant misdemeanist misfeasor mobster neglectful negligent nonpayer nonpaying not done not the thing off-base off-color offender out-of-line outlaw overdue past due public enemy racketeer regardless remiss roughneck ruffian sacrilegious scandalous shameful shameless sinful sinner slack tax dodger tax evader terrible thief transgressor undue unfit unfitting unlawful unpaid unrighteous unseemly unsuitable villain welsher wicked worker of ill wrong wrongdoer wrongful