cunning
The definition for cunning is "Showing clever insight." Used in a sentence: The general devised a cunning strategy to outfox the enemy.
duplicity
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.
implement
The definition for implement is "To carry out or accomplish." Used in a sentence: All Randolph needed to implement his plan was a moonless night and a long rope.
interminable
The definition for interminable is "Never ending, or seemingly endless." Used in a sentence: The impatient Zoe found the longwinded lecture interminable.
unscrupulous
The definition for unscrupulous is "Lacking principles." Used in a sentence: The unscrupulous salesman was fired for lying to his customers.