The definition for implausible is "Unbelievable." Used in a sentence: Claudia's implausible excuse failed to convince her teacher. The definition for curtail is "to make less.", the definition for fickle is "Lacking constancy, changeable.", and the definition for retroactive is "effective as of a prior time or condition."

The definition for heinous is "Shockingly evil." Used in a sentence: Eduardo's heinous betrayal of Lydia shocked even Latasha, who knew his evil ways. The definition for dubious is "questionable.", the definition for negate is "To make invalid.", and the definition for extol is "To praise highly."

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 stern is "harsh, severe.", the definition for implausible is "Unbelievable.", and the definition for commemorate is "To mark by a ceremony."

The definition for rail is "To scold in harsh language." Used in a sentence: Clay began to cry as his irate manager railed at him for missing the deadline. The definition for euphoria is "feeling of great happiness.", the definition for prominence is "Importance.", and the definition for supple is "Flexible."

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 stealth is "the act of moving secretly or unnoticed.", the definition for redouble is "To make twice as great.", and the definition for mediate is "To come between parties in order to reconcile."