derelict
The definition for derelict is "Abandoned." Used in a sentence: The derelict house was condemned as a public hazard.
dubious
The definition for dubious is "Questionable." Used in a sentence: Karl found Kevin's claim that he was sick dubious, as he had just seen him playing football.
exception
The definition for exception is "A case to which the rule does not apply." Used in a sentence: The teacher made an exception and let Gina eat her snack in class.
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.
futile
The definition for futile is "Without purpose, completely ineffective." Used in a sentence: Arguing with Andrew is futile because he never changes his mind.