The definition for euphoria is "Feeling of great happiness." Used in a sentence: Cassandra was overcome with euphoria when she met her long–lost sister.

The definition for impenitent is "Lacking remorse." Used in a sentence: The impenitent criminal received a harsh penalty, but his remorseful accomplice was released.

The definition for naive is "Lacking worldy wisdom." Used in a sentence: The naive Simon assumed that everyone was as simple and kind as he was.

The definition for polarize is "To break up into opposing groups." Used in a sentence: Thelma tended to polarize discussions rather than to encourage compromise.

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.