【Criminal】 , 【felon】 , 【convict】 , 【malefactor】 , 【culprit】 ,  【delinquent】 mean, in common, one guilty of a transgression or an offense especially against the law.

【Criminal】 designates one who commits some serious violation of the law, of public trust, or of common decency, as vicious unwarranted attack, embezzlement, or murder.

【Felon】 , the legal term for one popularly called a 【criminal】 , designates one guilty of a felony, which used with legal exactness covers all lawbreaking punishable by death or prolonged confinement (as in a state penitentiary) and is distinguished from a misdemeanor.

【Convict】  basically denotes one convicted of a crime or felony but has come more generally to signify any person serving a long prison term.

【Malefactor】  signifies one who has committed an evil deed or serious offense but suggests little or no relation to courts or punishment.

【Culprit】 often carries the weakened sense of one guilty of a crime, but more generally either suggests a trivial fault or offense, especially of a child or applies to a person or thing that causes some undesirable condition or situation.

【Delinquent】 applies to an offender against duty or the law especially in a degree not constituting crime; in its present semilegal use, in application to juvenile offenders against civil or moral law, it usually implies a habitual tendency to commit certain offenses and contrasts with 【criminal】  in implying a sociological or psychological rather than judicial attitude toward the offender.