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.

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.

The definition for incidental is "Minor." Used in a sentence: The accountant advised Justine not to report her incidental expenses.

The definition for preclude is "To rule out in advance." Used in a sentence: "Having cake now will preclude dessert later," said Amber's mother.

The definition for regale is "To amuse." Used in a sentence: My clever brother Jeffrey regaled the dinner guests with tales of his adventures.