cunning
The definition for cunning is "Showing clever insight." Used in a sentence: The general devised a cunning strategy to outfox the enemy.
foil
The definition for foil is "One that enhances or underscores by contrast." Used in a sentence: The sweet cookie was a perfect foil to the sour lemon sorbet.
interminable
The definition for interminable is "Never ending, or seemingly endless." Used in a sentence: The impatient Zoe found the longwinded lecture interminable.
naive
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.
obnoxious
The definition for obnoxious is "Highly offensive." Used in a sentence: The manager asked the obnoxious diner to leave the restaurant.