The definition for retroactive is "effective as of a prior time or condition." Used in a sentence: The retroactive law made even past infractions punishable. The definition for negate is "to make invalid.", the definition for penurious is "Extrememly stingy.", and the definition for exception is "A case to which the rule does not apply."

The definition for derivative is "Lacking originality." Used in a sentence: Critics panned the movie as a derivative version of last year's Best Picture. The definition for impenitent is "lacking remorse.", the definition for appalling is "Inspiring dismay or disgust.", and the definition for penurious is "Extrememly stingy."

The definition for unscrupulous is "Lacking principles." Used in a sentence: The unscrupulous salesman was fired for lying to his customers. The definition for melee is "a tumultuous fight among several people.", the definition for opportune is "Suitable or convenient.", and the definition for corrective is "Intended to correct."

The definition for duplicity is "Deceptive thought, speech, or action." Used in a sentence: The life of an undercover detective is filed with necessary duplicity. The definition for punctual is "on time.", the definition for heinous is "Shockingly evil.", and the definition for revoke is "To cancel by taking back."

The definition for illuminate is "To make clear." Used in a sentence: Her excellent lecture illuminated the complicated subject of nuclear physics. The definition for punctual is "on time.", the definition for fickle is "Lacking constancy, changeable.", and the definition for procrastinate is "To put off intentionally."