The definition for beneficial is "Helpful." Used in a sentence: there is no doubt that eating vegetables is beneficial to one's health.

The definition for epitaph is "Brief statement honoring a dead person." Used in a sentence: "Beloved by all,"" was the epitaph Edgar chose for his wife's tombstone.

The definition for moderate is "Tending toward the average." Used in a sentence: The best–selling writer was disappointed; his new novel was only a moderate success.

The definition for opportune is "Suitable or convenient." Used in a sentence: Quan stepped onto the platform at the most opportune time, just as the train pulled in.

The definition for retroactive is "effective as of a prior time or condition." Used in a sentence: The retroactive law made even past infractions punishable.