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 periodic is "occurring at regular intervals.", the definition for rail is "To scold in harsh language.", and the definition for recrimination is "A retaliatory accusation."

The definition for incumbent is "Necessary as a duty or responsibility." Used in a sentence: It was incumbent on Jack to attend his father's retirement party. The definition for proximity is "closeness.", the definition for gargantuan is "Gigantic.", and the definition for egotist is "Self–important person."

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. The definition for beneficial is "helpful.", the definition for immoderate is "Beyond usual or proper limits.", and the definition for oblivious is "Lacking awareness."

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 appalling is "inspiring dismay or disgust.", the definition for trove is "Valuable collection.", and the definition for incongruous is "Not harmonious, incompatible."

The definition for buffer is "Protective barrier." Used in a sentence: The dense trees acted as a buffer against the heavy rain. The definition for methodical is "performed in an orderly manner.", the definition for ethical is "Conforming to accepted standards.", and the definition for catastrophic is "Relating to extreme misfortune."