fickle
The definition for fickle is "Lacking constancy, changeable." Used in a sentence: The fickle Senji had a new best friend every month.
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.
parity
The definition for parity is "Equality." Used in a sentence: Hilda, to avoid squabbles, aimed for parity in the slices of birthday cake.
penurious
The definition for penurious is "Extrememly stingy." Used in a sentence: Ebenezer Scrooge was most penurious, refusing to give even a penny to charity.
revive
The definition for revive is "To bring back to life." Used in a sentence: Hank tried to revive Clare's interest in the project, but her enthusiasm had expired.