absolve
The definition for absolve is "To forgive; to free from guilt." Used in a sentence: Marta felt greatly relieved after her mother absolved her for breaking the vase.
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.
melee
The definition for melee is "A tumultuous fight among several people." Used in a sentence: After the game, a melee broke out between fans of the opposing teams.
placebo
The definition for placebo is "An inactive substance used in medical testing." Used in a sentence: Tom, who had taken the placebo, found that his allergy symptoms did not go away.
preclude
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.