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.
flaunt
The definition for flaunt is "To display showily." Used in a sentence: Sheila, who could not resist bragging, flaunted the "A" marked on her test paper.
lenient
The definition for lenient is "Mild or tolerant." Used in a sentence: The judge issued a lenient sentence because it was Frank's first offense.
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.
serenity
The definition for serenity is "Calmness." Used in a sentence: The serenity of the glassy sea soothed the sailors after the big storm.