The definition for diffident is "Lacking self–confidence." Used in a sentence: The diffident student never raised her hand in class, even when she knew the answer. The definition for incumbent is "necessary as a duty or responsibility.", the definition for foil is "One that enhances or underscores by contrast.", and the definition for retroactive is "effective as of a prior time or condition."

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 accentuate is "to emphasize.", the definition for heed is "To pay attention to.", and the definition for hedonism is "Belief that pleasure is the sole aim of life."

The definition for avian is "Relating to birds." Used in a sentence: The old man affectionately referred to pigeons as his "avian friends." The definition for eulogy is "speech or writing in praise of deceased.", the definition for frugal is "Thrifty, cheap.", and the definition for compulsion is "An irresistible impulse."

The definition for celebrated is "Widely known, respected." Used in a sentence: The fans waited for hours to catch a glimpse of the celebrated actress. The definition for revive is "to bring back to life.", the definition for revoke is "To cancel by taking back.", and the definition for mediate is "To come between parties in order to reconcile."

The definition for induce is "To influence or cause." Used in a sentence: The loud blast of the cannon induced an avalanche. The definition for inauspicious is "not favorable.", the definition for perception is "Capacity for seeing or understanding.", and the definition for pretense is "False intention or purpose."