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 mediate is "To come between parties in order to reconcile." Used in a sentence: The diplomatic Henry was able to mediate between the quarreling sisters.

The definition for negate is "To make invalid." Used in a sentence: Paula negated Tiffany's argument by proving that her main premise was false.

The definition for prune is "To reduce by removing excess." Used in a sentence: The candidate pruned his speech so he would not exceed the time limit.

The definition for rehash is "To discuss again." Used in a sentence: "Sandra," said her mother, "I am tired of rehashing this same topic over and over."