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 incidental is "Minor." Used in a sentence: The accountant advised Justine not to report her incidental expenses.

The definition for liability is "A person or thing whose presence or behavior is likely to cause embarrassment or put one at a disadvantage." Used in a sentence: Kevin's growing fatigue was a liability as he attempted to climb the steep hill.

The definition for nurture is "To further the development of." Used in a sentence: Our cat made a nest of blankets to nurture her newborn kittens.

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.