adversary
The definition for adversary is "One who opposes or resists." Used in a sentence: Franklin hoped to defeat his adversary in the afternoon's tennis match.
incidental
The definition for incidental is "Minor." Used in a sentence: The accountant advised Justine not to report her incidental expenses.
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.
revoke
The definition for revoke is "To cancel by taking back." Used in a sentence: After Kal's father revoked his allowance, he had no money for the movies.
surplus
The definition for surplus is "Excess." Used in a sentence: Trevor decided to freeze the surplus chili for next week's tailgate party.