The definition for curtail is "To make less." Used in a sentence: Doreen decided to curtail her spending after she bounced a check.

The definition for derelict is "Abandoned." Used in a sentence: The derelict house was condemned as a public hazard.

The definition for diffident is "Lacking self–confidence." Used in a sentence: The diffident student never raised her hand in class, even when she knew the answer.

The definition for ethical is "Conforming to accepted standards." Used in a sentence: Mary did the ethical thing and turned in the diamond necklace she found.

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.