The definition for colossal is "Immense, enormous." Used in a sentence: After pushing with all his might, Frank realized he could never move the colossal boulder.

The definition for dubious is "Questionable." Used in a sentence: Karl found Kevin's claim that he was sick dubious, as he had just seen him playing football.

The definition for insolence is "Boldness or rudeness." Used in a sentence: The boy's insolence to the policeman embarrassed his mother.

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 repel is "To resist, reject." Used in a sentence: The soldiers made a massive charge to repel the invaders.