The definition for corroborate is "To support with evidence." Used in a sentence: "Unless you can corroborate your story, it will not be admissible in court," the attorney told his client.

The definition for eloquent is "Fluent, expressive." Used in a sentence: Kim, an eloquent speaker, was the best choice to make the presentation for the group.

The definition for impenitent is "Lacking remorse." Used in a sentence: The impenitent criminal received a harsh penalty, but his remorseful accomplice was released.

The definition for oblivious is "Lacking awareness." Used in a sentence: Love–struck Charlie was oblivious to everyone but the object of his affection.

The definition for redouble is "To make twice as great." Used in a sentence: As the sun began to set, Brittany redoubled her effort to find the necklace she had dropped in the field.